I was asking around on the WoW forums which arguably did no good. So I came here.

Come 2.1 the Collar of the Engineer will be point for point better then Spellstrike Hood.

The contender:

http://www.wowhead.com/?item=29986

and we know it we love it the reigning champ:

http://www.wowhead.com/?item=24266

All together the Collar will have +15 Int +5 Stam +7 Damage +8 Crit over spellstrike.
Opposed to 5% proc of a 93 spell damage for 10 seconds - This only procs on application of spells not DoT ticks.

Which overall would be the highest DPS? To me they seem kinda even in the trade off and worth it. Any oppinions?

spellstrike procs off any spell hit, which means it procs constantly when you're AEing so it's obviously better for that.

as for chain casting shadowbolt, with a 2.5 second cast time, lets add 500 ms lag, so 3 second cast time that's 20 spells per minute so 1 spellstrike proc per minute or an average of 15ish spell damage.

add to that a number of instant cast DoTs and your proc uptime improves a bit. for an affliction warlock I'd say there's no question that spellstrike is better if you're getting the 2pc bonus.

Indeed the Collar is (very) superior point by point. Having no red sockets and a +spell damage socket bonus is a bit annoying for me though. I would clearly shift from SS hood to this Collar if I got it - I'd also guess I might have found a legs slot improvement at this time, thus in summation upgrading well above the 2 piece set bonus too. Assuming that a cast rate of 3 spell hits in an average 10 second proc duration, SS set bonus proc boils down to 12 +dmg per spell hit (92*(3/23), 3 out of 23 hits, given that the 5% proc rate is correct). Scorch spam could ofc put you up to 6-7 spell hits in a 10sec period, but the lower +dmg coefficient would effectively bring it back down. Sorry if I'm being a bit fire mage specific here

This being said, I think a more interesting competition would be the Collar versus the new Destruction Holo-Gogs.

With the addition of orange hit gems (Veiled Noble Topaz - 4 hit/5 damage), I'd say yellow sockets are just as good as red unless you're already at the hit cap and can't swap any of your gear around.