The way to approach this is consider the numbers
with a glyphed CoH you'll hit 6 targets, at 16% crit its a near guarantee that you should see a crit
with PoH you could at most hit 10 targets, but once again 6 is most likely (pets) the 10% bonus from tier 8 means that at baseline stats you are almost always going to crit with PoH
PoM bounces 5 times, during that, 5 chances to crit, 6 if tier 7 still, if 5 20%, if 6 once again 16%
as far as the math on your crit goes, consider it takes 45.3 crit strike rating to gain one percent of crit
If you have a 1-6 chance of getting a crit i.e 16% in order to get to 1-5 you need 20% a gain of nearly 181 crit strike rating, to 1-4 you'll need 227 crit strike rating in addition to that.
As far as haste goes the maximum before hitting the GCD cap of 1 sec is 33.3% or ~980 Haste, anymore than this and I think the devs have gone back to thinking about fights like twins.
Your spellpower is one of those stats that a lot of folks will tell you to aim for 2k, that's a fair number but the general consensus has always been, more spellpower is not going to hurt you unless you have regen problems, folks that claim a higher number than 2k are thinking about a raid buffed number
Int, Spi, and Stam, just take what you get, Int contributes to crit and your regen nowadays, for crit 167 int = 1% crit at 80
As for Ratios of spirit to int, due to the changes to holy conc, the ratio skewed from its post-tbc 2:1 factor to a (2.7-3.3):2 factor. If your spirit is much higher your gains from holy concentration will be offset by the diminished power when spirit exceeds the original 2:1 factor still in the game you will see less significant gains in terms of mana regen during those procs.
The real bitch of this is whether you talent imp renew or not, if so you can almost always force the proc, if not at the very least an unhasted flash heal can be cast 5 times before holy conc fades, so 20% crit would be required to realistically expect to keep this talent up. If you toss your pom out, as little as 10% would be reasonable enough considering a raid damage fight.
Spirit in and of itself is still a strange stat just because of human priests' human spirit racial, in that the numbers are actually slightly different, not by huge amounts but enough to be noticeable.
Most all of these points are moot when compared to the simple fact that disc and holy are very different playstyles.
http://www.wowarmory.com/character-s...n=Faded+Dreams