Looks like you've got a good combo there, Snubbie. It seems the burners with the holes facing up work better with the Olicamp than my side hole Giga stove burner does. (Makes sense if you look at the burner on a Jet Boil).
Just for kicks, I tested some MSR fuel against the Giga fuel. Same-same, in the 4oz size (new cans), and they each used about .4oz of fuel per burn.
Darn I missed the obvious. Those ARE side burner holes on your stove rather than top.
I still don't understand why it wouldn't boil faster with the XTS unless it just doesn't use the flame any more efficiently for some reason...but that's a "duh". Obviously there is no gain for you...I'm still scratching my head on that one.
