I love the idea of a 4000 lumen light only using a single LED emitter. But, I am going to hold off a while before buying anything to supplant any of my 1000 lumen lights.
That XHP-70 is slightly less efficiency than the XM-L2. So, I would make a wild-ass speculation that if it's putting out 4 times the light, it will last 1/4 the amount of time on the same amount of battery. Thus, I can see why the XHP-70 is setup to take 2 x 26650s. If you were going to run it on High for a whole dive, you would need that much battery (or more).
Also, I hate that style of switch. I have a light with that style and I found it constantly getting bumped and turning the light on by accident while clipped off to my chest D-ring. And with it pointing down and slightly back I often wouldn't notice. Not to mention the opportunities to have it accidentally on when in my dive bag or elsewhere if I leave the battery in it.
Holding 2 x 26650 or 18650 batteries also makes it longer than I would really want to deal with. Definitely too long to mount it in a soft Goodman (aka light sock) on the back of my hand.
All that said, running that light at 1000 lumen (equivalent) output, it should last even longer than running an XM-L2 on High. So, maybe someone will make something with an XHP-70 that only takes 1 x 26650. 1000 lumens is plenty bright for just about anything I've ever needed. The smaller size of only holding 1 battery would be very desirable. And then the ability to crank it up to 4000 lumen output for short periods on an as-needed basis, would be pretty sweet.
Otherwise, I'll be keeping an eye out for an inexpensive can light that uses an XHP-70 and still gives at least 2 hours of burn time on High. A light head with one of those in it should be nice and small and still incredibly bright! And a video light with 3 of them would be really awesome!
