is there a any argument to use Torx bolts over hex or the other way around?
Torx is superior, always use them in preference to hex if you can. The driving interface is larger and much closer to orthogonal to the driving force, so the pressure is dramatically reduced, making 'rounding out' much less likely.
Requires a multi-tool not designed by interns, though. Got to the Alps before remembering I needed a torx I didn't have to re-tighten my ritchy stem bolts. BAH.
Torx is superior, always use them in preference to hex if you can. The driving interface is larger and much closer to orthogonal to the driving force, so the pressure is dramatically reduced, making 'rounding out' much less likely.