Second, this is a listing of things people need to be aware of/consider when they are deciding if getting hit cap is good for them or not. There is a lot of information about this spread all over a billion threads and I thought it might be helpful to have a listing in one place a person can easily look at. This is not meant to be an endorsement of either method though. If you think I left something important off my list PLEASE post and let me know
Ok, now to the fun stuff. Also note... this list is in no particular order just as I thought of things/they were suggested. So don't assume that the first thing is the biggest deal thing and the last thing is moot.
What is Hit cap?
17% or 1742 hit/spirit (1639 for Draenei)
What hit rating equals 1% hit?
102.446 rating = 1% hit
10.2446 rating = 0.1% hit
Also if you want an easy way in game to tell how much your will gain/drop in hit (and any other stat) without having to calculate the math RatingBuster is a great addon for that.
Hit cap is a hard cap.
Basically once you get to 17% if you go over 17% you get no further benefit. In some ways being at 17.01% is bad in the sense that you probably are not maximizing your stats somewhere. That extra 0.01% does absolutely nothing for you. Because of this some people prefer to be just under the cap instead of over it.
How's your Latency/FPS?
The whole being under hit cap works because with the exception of one spell (leaving sw: death out for the moment) all of our spells can immediately be recast if we miss on it. This limits the affects we feel from missed spells and is the biggest reason why there is any discussion about not getting hit cap now. If you have high latency and/or you have low FPS you ability to react to misses will be affected since you won't be reacting as quickly.
Even if you miss on MB you still get the ES buff.
One thing people say as a reason to not go under hit cap is that ES might fall off. This is simply not true since you get the ES buff from casting MB not from MB doing damage.
What about the fact that MB does a lot of damage and after 4.2 it does a larger % of our damage than before?
Yes missing a 3 orb crit MB would seriously fail. However, the things to know about that is a 3 orbs and a crit is a best case situation which doesn't happen with frequency. Also, if you are making use of your buffs properly and paying attention to your priorities you will be casting MB far less often than your other spells so you would be less likely to have a miss occur on a MB as opposed to happening on other spells.
Also MB does do a little bit more of our damage than before, however it's not a huge percent more; basically the majority of our damage is not coming from MB yet. However, when you get the T12 4pc bonus missing MB becomes a bit more of a deal, so you should always be keeping an eye one what you are missing and if you find you often are missing a MB you might want to try adding some more hit and seeing if that helps.
Misses are calculated on the cast not on the ticks.
Just wanted to mention this because I saw someone say that even if you hit with the spell the ticks could miss... which is completely not true.
Even if you hit with DP you can miss with Imp DP.
Hit is calculated separately for DP and Imp DP so one can hit and the other can miss. This is mostly important because above boss health of 25% some people spam DP on movement or at the end of fights because the dps increase from the Imp DP part is worthwhile. Being under hit cap would make this potentially less effective.
Missing SW: Death is awful.
If you need to use sw: death for mana regen yea, missing it would hurt. Also, missing a sw: death under 25% boss health would also hurt because it does a good amount of damage and if you miss the first one the CD doesn't reset and you can't recast it immediately. However, similar to MB you cast far fewer sw: deaths so it is less likely a miss will occur on the sw: death instead of on something else. This gets skewed a bit at the end of fights when we spam sw: death as much as we can.
Missing VT you might not be able to recast immediately due to movement.
On some fights missing a VT absolutely can cause problems because there might be a second or two where you might not be able to recast it. Much like best case scenarios, worst case scenarios don't often happen. It is something to be aware of though.
What's the lowest hit rating I can use and still do great dps?
Kilee did a good explaination of this so I am just going to copy it here.
Kilee wrote:As far as what simcraft tells you, you don't start noticing negative dps effects until somewhere below 14%. I've seen sims go as low as 11% with no negative effects.
The higher your gear level, more important hit affects you. At 346 ilevel, you can almost ignore it if you're doing everything else right. Once you start hitting 372, the misses hurt more and affect your potential dps in more profound ways.
Also, it can not be said enough but the point at which you personally see a reduction of dps is not something anyone else can tell you. You really have to try different things and see what works.
How good are you at following mechanics, changing targets, and noticing misses?
There is a lot going on in raids at one time. If you are going to drop below hit cap you are adding another thing to your plate here. In this case you might see a drop in dps at first because you might have to practice to make the most of being under hit cap. How long you need to practice and how long your raid leader is willing to wait for you to get it together might vary (some raid leaders might even say they won't take you if you are under hit cap). For this reason some people prefer to be at hit cap for all progression fights and only go under for farm content.
Addons that are used to track DoT durations can be fooled by a miss.
Sometimes when you cast a spell the addon you use might assume because you cast it that it hit and will show you that the DoT is on the target, only to randomly disappear a few seconds later. The upshot of this is if you are using an addon to track your misses it can slow down how soon you recast the spell and can result in a loss of dps.
Lower ilvl gear with hit is almost always a worse choice than higher ilvl gear without hit.
Often during raiding because loot is random, we are put in positions where we have to compare a higher ilvl piece without hit to a lower ilvl item with hit. The reason the higher ilvl piece will almost always be a better choice is that the higher ilvl piece will have more int. Int is by far our most important stat (normalized values int at 1 and any other stat at 0.4 something). For this reason having the mentality of "I will never go below hit cap ever" can cost you.
This point gets slightly murky depending on your abilities and if you start dropping too low on hit cap. A good idea is to figure out a range you are comfortable with having your hit at. If you are less that 1% under hit cap though, most fights you won't have any misses at all. It is a numbers game though.
This will get a bit interesting in the current tier because the majority of our spirit/hit gear is going to be coming from craftables/vendors. What this works out to is once you get get the ilvl 378 gear and you are still seeing ilvl 378 gear drop, you won't have to deal with this issue. However, going from ilvl 372/359 gear to ilvl 378 gear you will probably face this issue often while you wait to get enough valor to but your spirit/hit pieces and to get the other pieces crafted. You will also see this issue once you have ilvl 378 and ilvl 391 starts dropping and you are working on collecting enough shards to upgrade plus craftable gear can't be upgraded.
The more under hit cap you are the more likely misses will happen.
Obvious, but doesn't hurt to say it
If I sim it and it says I should go haste over hit, but in game I do more dps with more hit I am doing it wrong?
Well no... not exactly. Basically, running a sim cannot account for all the things about you personally which might affect your personal relationship with hit. Sure it has different settings for different skill levels, but as in real life some people aren't good at honestly accessing their own skill level. If you run a sim and it tells you hit is not at all important, but when you do this in game and your dps goes down, then it would be sort of dumb to keep doing it. Sure it does probably mean you have some things you need to work on (like noticing misses, keeping dots up etc) and it sometimes takes awhile to get that worked out. You have to be honest with yourself and realize if you do or do not have the time/patience/forgiving raid leader to let you work that stuff out.
I am new to shadow, so I heard I don't need hit right?
Personally I would say get hit cap at least until you feel comfortable with how we play. Not being hit capped further complicates our playstyle which is already a little complicated. However, if you want to not worry about hit cap from the start that's cool. You just really need to be willing to adjust what you are doing if things aren't working out for you. Actually that last part is true for anyone no matter how long they have been playing a spriest