I have Gene's M60L but don't have the SF LED to compare it with. Gene's M60 and M60L are the same optic/led/etc just the current is 500mA instead of 1A.
It puts out a lot of light and has a nice gradient beam. I really like the longer runtime - you get more than half the light and three times the runtime...
It is an optic, rather than a reflector. There is some fine structure to the beam pattern, but the gradient pattern is very nice. No rings, doughnuts or edges.
I ran the M60L for 20 minutes last night in the round body 6P at Gene's suggestion to check the heat transfer. I used a pair of 3.7V rechargeables. The outside of the light was not detectably warm. Quickly removing the drop-in, I could feel a very slight rise in temperature in the brass body. Barely detectable.
The decision process for selecting between the M60 and the M60L was hard. The L was more available. My first thought was to wait as long as it took, and with Gene going full-time that was likely to be easier. I had just missed a batch. So the choice was between 235 lumens for 1.5 hours, or 140 lumens for 4.5 hours. The more I thought about how to make my old 6P useful, and how many other flashlights I already have that are in the neighborhood of 235 lumens, I wondered if that brightness was necessary and worth the shorter runtime. It is less than a one stop improvement (doubling) for a three times decrease in the runtime. It is a noticeable brightness difference, but not a huge one. It is almost exactly the lumen values of a Fenix P3Dq5 on high versus turbo. Just how often is turbo needed to do something that high won't do? We're already at about double the old incan output with the M60L! So for a three time increase in runtime, I'll take the M60L. I'm still not precisely sure how I'm going to use this reclaimed old 6P, but it now has an efficient and very bright long lasting rugged light engine that works with primaries or rechargeables and I am going to use and enjoy it a lot.
-- Alan