If you don't want any spill, you should avoid a conventional reflector light. This leaves 3 options:
(1) Aspheric lens with LED - this is probably your best bet. Someone on BLF converted a BLF GT with a giant aspheric lens. Result was a nice pencil beam with no spill and something like 3.8 million lux.
(2) Aspheric lens with LEP - like the Acebeam W10. LEP modules (powered by lasers) offer twice the intensity of the best LEDs. They're the pencil-beam throw kings for their size. However, something like a BLF GT will still easily outthrow the few LEP lights out there since all the LEP lights use relatively small lenses.
(3) Recoil thrower - this is a type of LED light where the LED is mounted on an arm near the lens and points backwards into the reflector. They produce narrow beams with no spill like aspherics, but without the light losses into the sides of the bezel that aspheric lenses typically feature. Downside is all the recoil throwers are old. Nobody has made a recent recoil thrower. It would be awesome if someone made a nice recoil thrower using modern LEDs with an LED arm made from solid copper.
