Well, the XPL's can go pretty high in current, much better than the XM-L2's from my seeing/testing. 6.5A should be no prob for an XPL that I've tested, think anyways, not sure if the newer ones are worse though.
Not sure what you are hinting at with the buck driver, but sounds all good - would love to see it. If you are referring to the Texas Buck driver series here, the OP sounds like there's a way to go, but not sure if that's accurate.