After some communication with edgetac, a jetbeam customer service rep, it is ok to use a 14500 li-ion battery in this light.
It uses a boost circuit which is bypassed when using a higher voltage li-ion battery.That means it will run in direct drive and put out significantly higher output. So the circuitry can handle the power, but operating temps have to be kept in check to avoid thermal damage to the components or emitter. Should be fine on max for a couple of minutes at a time.
I'm definately picking one up after veryfing this information. Now only if they would produce a matching clip for the light.