I think this ability is currently broken. I am in approximately BIS non-hardmode gear and the calculator gives me the following.
Rip DPE: 2513
Ferocious Bite (35 Energy) DPE: 730
The risk of doing a FB is substantial, to get so little reward for it is not good game design. To take such a risk when the reward is only 400 DPS, if you pull off 1 per minute with with no decrease in uptimes is rarely worth it. Now we know Blizzard will not increase FB damage because of PvP but what could and should be done is to lower the energy cost to bring it inline and redesign Feral Agression to lower energy cost further. We've already known Feral Agression is considerably underbudget. Not that Blizzard considers it a huge deal if talents are overbudget or underbudget but here is a way to fix multiple problems that should be a win/win situation for everybody. Decrease FB to a flat 25 energy and change Feral agression to reduce FB cost by 2 energy per point.
Pros:
Feral finally gets rid of the energy conversion they have hated for so long.
FB becomes a good ability without making it a clone of a Rogue ability.
FB becomes a viable finisher. In my gear it would change to.
Rip DPE: 2513
Ferocious Bite (15 Energy) DPE: 1705
No more QQ about huge FB's in PvP. Well there will always be QQ about everything but FB will hit for less in PvP.
Cons:
None that I can think of.