"Most" decent RY4s will have a good blend of the caramel and the vanilla to the tobacco.
I've had some that were outright horrid, and most B&M RY4s are in that category of horrid (see the Rev's post). I've managed to mix up a few variants of RY4s that I personally really enjoy (adding cherry (not the cough drop tasting variety, either) or peach to the flavor is pretty good, IMHO). Tribecca, like you noticed has a slight "nuttiness" to it, that almost any other RY4 will not have. I've yet to see a successful vendor/ B&M made 'Becca clone (thankfully). I also on occasion pick up some minor whiffs and notes of a chocolate in it, but its really in the background.
I think its the complexity that I like about it, same with almost every other Halo juice, nice complex flavors. Even the ones like Torque and Turkish are more than one flavor ponies.