In reply to david glancy:
As above, I think the Primus is better, but certainly on Aconcagua all the sheeple will be using XGKs, so spares will be easier to find. However, assuming the Omni is the one that also takes canisters (Primus put two out, one did, one didn't, the latter being cheaper), and they sell canisters in Mendoza (plus leftovers from other expeds), that gives you a fuel option over XGKs.
Obviously XGKs are not crap, far from it, I just think the Primus is a bit better. I have also had a Dfly but that WAS crap and I no longer use it. Lots of bad reports around on Dflys. I found the screw thingy in the flame adjuster clogged too easily and that I never really used the adjuster anyway - I just melt snow and boil water. Also had O-ring problems and a sub-standard plunger cup, but they're not specific to the Dfly, as far as I know.
D