Been there done that with one of the aspherics from Surplus Shed.
Used a Cree. It is really cool but really only usable for me for just one thing......long distance spotting. With a long lasting battery setup you would be able to run it forever unlike an incan or HID solution. That said, the incan or HID solution would in my opinion be at least twice if not three times brighter minimum that any LED solution.
The only exception would be the lense out of the Subaru that one of our CPF members modded. That was really cool. My mag......OK.
I mainly use my LED
M@gs for close in room or small area lighting and not spotting. That's what the HIDs are for (and they do it very, very well).
Bob E.