Better accuracy according to whom? Also, if you're that concerned with accuracy, why do you want 7.62x39 (which isn't exactly known for accuracy or shooting flat)? All the reviews I've seen say accuracy is very good (1 MOA with ammo it likes) and I've seen no reviews for the Beretta that talk about how accurate it is. Yes, bullpup triggers are generally not so great but the Tavor's is the best of the bunch. However, the Tavor's trigger can be improved quite a bit with an easy modification, and I'm betting some polishing in the trigger group will make it even better.
Why do I want a Tavor? Because it's the shortest rifle you can get without going to an SBR, it's currently the most battle proven 5.56 rifle out there, short of the AR/M4/M16 platform.
I already have an XCR and I'm not seeing how the ARX would do anything better than that, other than support from the factory of course.