I have both I'm swapping back and forth between them. I guess the obvious answer is you can see your
juice with the vortex and it's SUPER easy to fill. The fluxos aren't bad to fill once you get a syringe with a needle, but I like not having to use a needle. I do use a pipette to fill the vortex because I'm a little clumsy.
The metal fluxos do feel sturdier, I've only had leaking problems with one of them because I took it apart and there's no inner gasket on the metal ones like the clear ones, so they may leak (it's a small leak and only one of the two I messed with do it). I posted earlier with my leaking experiences on the vortex, so that's good but I do wish I could keep a drip tip on them all the time as the caps are super loose.
Burning wise, I do get a little burn on the fluxos if I back to back hit them. A short rest of say 10-15 seconds in between hits usually takes care of that.
I've gotten burnt taste with the vortex but it doesn't to seem to happen so easily, and it seems to happen more with an ALF than without.
As for HW, I'm using an eGo USB PT, my
juice is generally 80/20 or thereabouts, though I do have a 100% VG cinnamon that does well in a metal fluxo... don't try that in a vortex