You can't compare us to ret paladins... It's like comparing apples and oranges.
About Horror, it's same with all disarms, they will last 50% shorter. The horror effect however will always be full. It acts almost the same as locks DC just without healing component and even when a player gets dispelled the disarm effect still stays.
Prot warriors? I'm yet to see one in arena (2390 MMR Godcomp at the moment). And you're talking about 2s? Sorry didn't see that, spriest has lots of issues there but as many have pointed out, it's 2s it doesn't matter.
And I play with druid, not shaman
I find it hard to keep procs up only against shamans in 3s, in that case I'm just using them right away to keep the pressure up and build up orbs. If mages sit on the spellsteal, then they won't have mana for doing damage. Frost DK icy touch spam has hard time taking off procs when most of the time I have renew, hots from druid, shield up. Hunter's same as mages, using focus cripple their damage.
And I would say you are very unlucky about the MD.
And your point is right, playing with mages is lots easier, but last night we were queing into 5 different spriest setups (shadowplay, shadowcleave spriest, heroic RLS, warrior/spriest/paladin, feral/spriest/shaman). We won most of the games, but many of them were pretty close.
Thing I'm saying, spriest is strong at the moment. Off-heals are still decent enough to keep your partner alive when your healer eats the CC, damage is good, MD is OP. And we can operate without mage holding our hand it just takes practice (I'm having hard time against warriors and ferals at the moment, rest are 50:50)