I'd go for LI over Blood talons if you're looking for better pressure in 2s or a team with tons of peels/longevity.
On topic though, the only problem I've really had running jungle was running into ret/hunt/disc where they can just tee-off the traps on your priest with a hoj while saccing theirs when you manage you pull a chain. I'm hoping that once we see locks and mages get some buffs we'll see some more FMP again: I loved that comp in Cata.
The other thing to consider with mastery is that if you're running a pressure comp and rolling bleeds, you'll probably be running lunar inspiration as well; which mastery does not affect. So you're probably better off investing that in crit and vers anyways.
The only advantage of crit is additional CPs every now and then. Otherwise versatility shits on crit in PvP both for damage and for survivability simply because additional damage on crits is halved and cats already have decent baseline crit.
Yes and no. Back in Cata and wotlk, ferals would sit around 36% crit in pvp gear and mangle would generally provide a slightly faster combo. Even stacking crit right now, you're probably sitting around 32-34%, and if you're stacking vers, you're probably going sub 30%. It seems negligible, but I've always found that 35% was right around the sweet spot for rolling dots and keeping pressure; any less and dangling on 3-4 point combos too often and losing rip uptime.
Certainly, once there's more gear, I'd recommend hitting that 35% and then putting as much as you can into vers. The question right now is: is the damage reduction (currently like 2-4% depending on how much you stack) worth the combo gen? Damage-wise, it probably breaks about even. I think we're just desperate for any amount of damage mitigation we can get.
Of course, your playstyle is also important: if your comp is lining up kills with inc and zerk up, then pressure and combo points are pretty meaningless and that crit isn't as important.
I think as we see arenas slow down and long-game pressure comps make a comeback, you'll still see vers, and by then our passive crit (without stacking it) will probably be high enough that it's a non-issue.