Ferocious bite is really REALLY weak though, you're right that its ideal to bite aggressively to not waste combo points, but I think you may be overestimating the importance of doing so. Personally I don't think that all the possibilities are perfectly represented in the sims - a sim will outdo a player on average but doesnt have the same kind of malleable logic that a real player does.
Looking at the numbers for conatzer, FB's DPET is only 16% of Rip's, so TFing rip is going to very nearly make up for that damage - if you add one shred it brings it about equal. If you don't already have a thrash up, thrashing that excess energy should actually put you ahead of using FB. Since in practice its hard to be perfect about clearcasting procs, I've found occasion to essentially do just that quite often.
My guild is kind of sucking atm and I havent got lucky enough to get any tier gier in LFR, so I can't give any anecdotal evidence for the efficacy of this, but I expect either way will net about the same dps for a real player, though a computer may see more benefit with the aggressive FB profile