Hm... you're right, I wasn't being rigorous enough there. It would be accurate for hit rating, but for expertise CS and J should really be treated independently. However, if we're going to go to that level of rigor, we need to do so more accurately than you did.
First, Judgement isn't 1 HP every 6 seconds, it's rotationally constrained to 1 HP every 6.75 seconds.
Second, you get 1% expertise for
340 expertise rating, but it takes
425 haste rating to give you 1% haste.
So, rigorously then:
A = C*(1 - m + dm)*(1+h+dh)*1.2 + J*(1+h+dh)where
C is your CS rate (1/4.5=0.2222)
J is your J rate (1/6.75=0.1481)
m and
h are decimal dodge/parry and haste values (assuming 7.5% hit - the earlier version is enough to prove hit>haste)
dm and
dh are added expertise or haste.
Expanding this and ignoring second-order terms (i.e.
dh*dm), we get:
A = 1.2*C*(1-m)*(1+h) + J*(1+h) + 1.2*C*(1+h)*dm + (1.2*C*(1-m)+J)*dhWhat we're really comparing are those last two terms:
Ae=1.2*C*(1+h)*dm and
Ah=(1.2*C*(1-m)+J)*dh. But we want to do so in terms of rating
r, and since
dm=r/340 and
dh=r/425, we can write:
Ae=(1.2*C*(1+h)/340)*rAh=((1.2*C*(1-m)+J)/425)*rFor
h=0,
m=0.075, we get
Ae = (7.8431e-4)*rAh = (9.2897e-4)*rSo at 0% haste and exp soft-cap, haste is about 18% better for HPG than expertise. Conversely, it takes about 18.44% haste before expertise catches up to haste.
So yes, haste is actually better for holy power generation than expertise. That doesn't really matter though, since the advice to hard-cap expertise isn't based on raw HPG or SotR uptime. It was based on damage smoothing, and
in those simulations the hit/exp capped gear set out-performed the soft-capped gear set that stacked haste.
The difference wasn't huge, but it was also a stochastic simulation (i.e. get as much SotR uptime as possible). In practice, a good player is banking and using HP intelligently, and the certainty that your next generator will hit has even more value there. Nothing sucks more than missing a Crusader Strike and dying to the next melee attack because you couldn't refresh SotR.