Observer VS Fel IMP!

[jason1975]

If you lack melee debuffs guess what happens to a melee pet . . . .

With that big differential, I'd check to make sure that Observer is not getting knocked back and that his attacks are on auto-cast. Frankly I'd go imp or Shivarra on that fight so I didn't have to worry about it.

[Greeneye7]

So after using my pet for dispels on Sha of Pride in LFR i happened to notice the same thing. Im using recount not WoL but here are the results (DPS included, not just damage done)
Attempt 1 Wipe - Observer
Time of Attempt : 322.99 Seconds
Damage Done : 5228688
DPS : 16,188.4
Attempt 2 Kill - Fel Imp
Time of Attempt : 472 Seconds
Damage Done : 7651591
DPS : 16,211
Hope this helps to clear the air a little bit, They are about equal
This was with near equal uptime on the Power of the Ancients buff. It is really just fight dependant. Imp = Lots of swapping Observer edges it out on patchwerk. But if you need interrupts go observer, or dispels fel imp.