Ugh - you're right, not sure then. A MtnE style boost is probably wayyy too much $$$, and yes, limited amps. Hhmm. Ok, I get it now - the 3V XHP50.2 might be a better option, but in theory, you should get more efficiency of lumens/amp out of the 70 with a decent boost driver. I really dunno why our boost driver prices are sooo much higher than what they do in China, but then again, lot of the China boost (or buck) drivers we've used turned out to be unreliable in the long run, probably over amped them or the quality of the parts, etc.
Because of the driver. FT02 uses boost driver which is more expensive.
But I think XHP70.2 is too much for this host. Simply not enough mass in the head and no fins just those little ribs on the neck. An L2 head is 90g more weight and it has smaller diameter. With SST40 it has good balance but XHP70.2 is a no go for me in this light. Even a 3V XHP50.2 can make a lot of heat and current.