I currently shoot the Halon 6 and this is what I have noticed when shooting the VXR 31.5.
Biggest Differences:
Halon 6 feels top heavy, VXR's extended riser makes for a very balanced bow. To combat the imbalance in the Halon I recently bought a back bar stab and it has helped quite a bit.
Halon 6 is 4 fps slower through chronograph
Halon 6 is very dead in the hand, however, VXR is even more so.
Is it worth upgrading? Not for me, but I am a recent college grad working my ass off as a mover at a moving company for a little spending money until my "big boy job" starts in October.
If you have the money to cough up for the VXR, do it, best feeling bow I have shot. If not, don't sweat it. 2021 bows are right around the corner anyways.
I plan on restringing my Halon after this season and keeping it at least three more years. A lot of thought went into my decision, it really just depends on your budget.