Bagman, I've had chop (Tony) mod a couple of KL3 heads for me and very much like how they turned out. These work very well on the G2/G2Z since they have plenty of mass and cooling fins for handling heat well.
The latest one uses a Lux III TVOJ with the stock circuitry modified to run at about 850ma. He used a Pelican Reflector instead of an optic. It is very white and bright and will have good steady output runtime.
The beamspot looks alot like a McLux PR with Lux III and driven in the 800-917 range. Spill and throw are very similar to the McLux PR or PR-T.
The first one chop did for me has a TWOK Lux III at 1.2amps and uses a Fraen LP optic.
There are others like CM who do fine work with SF LED heads as well.
Britt