The Fenix is designed from the ground up to be a LED light.
The Surefire is an old design from when thermal isolation was never considered a problem. The default P60 LED that comes with the Surefire offers absolute, ultimate reliability retrofit to an older design that is normally fairly hostile to high output LED's.
Malkoff offers a different solution with better heatsinking and an optimal thermal path, allowing him to drive LEDs harder and longer (more efficiently) than Surefire's design, but they increase weight by a few ounces over the Surefire way. It is a most worthwhile tradeoff, one which Malkoff is able to offer because he is a small custom maker.
New SureFire C-series LED lights (includes G2L and 6PL) as of SHOT 2010 have an upgraded thermal path and an integrated LED module, allowing them to be much more comparable to the Fenix, etc, in output, with 120 lumens for several hours.