Quite controversial issue here in the forums, So I will try to remain impartial.
For V brakes, try some different pads first before you go through the expense of switching to disc brakes: Kool Stop salmon compound. See how those work for you.
Yes, disc brakes will also overheat on a long descent and you'll wear your pads quickly, too. You can minimize that with putting a larger rotor up front (e.g. 180mm), but the ones that come stock should work really well. You may have to play a liitle with that after a few tours. An advantage that many point out is that with disc brakes (besides amazing stopping power) you don't wear out your rims. It's usually easier and cheaper to change a rotor than an entire rim.