Today I received two M61NL dropins together with another two Keeppower 16650 2500mAh cells. Awesome beam profile and tint with a very good compromise between brightness and runtime.
The luxmeter confirms that the XP-G2 M61NL is brighter than XP-G M61WL. I placed one of the M61NL in my Surefire G2L fire rescue host. I have not yet decided where I will put the other M61NL. The possibility to use 17670 and 16650 cell is very good with Surefire G2 models. The brightness is lower with 3,7V Li-Ion than with 2xCR123 though: as with predecessor M61WL(the first generation with XP-G was around 5000K though it was called warm) the brightness with a Li-Ion 3,7V cell is ~80% of 2xCR123 cells. Not a big difference for the eyes but much more economical and I think definitely better runtime with 16650 2500mAh cell than with 2xCR123.
I feel that while the technical development results in higher and higher efficiency and performance, all is not about the highest possible efficiency and performance. I think these Malkoff dropins are pretty timeless and they will still be used decades ahead. No overheating issues and no need for special ultra high drain cells. I have great multimode lights but I really like the simpleness of single mode as well.
Malkoff dropins are "no nonsense" devices when they are as best!
There is only one thing I like better with the first release of M61, however: the hotspot of XP-G dropin is more punchy than with XP-G2 which looks a bit "fuzzy" in comparison.