I would think that if you like and use the original M6, the new one will be largely superior. I looked at one recently, and seriously considered getting one. The only thing that really kept me from going for it was the fact that it is a single mode, which makes it a nice, fairly high output spotlight, but not very useful for much else, so I opted for the UB3T Invictus. (I thought that light was more versatile, which matched my use better, but of course it might be precisely the opposite for you.) I was tempted by the M6LT - I think you'd find it a very nice upgrade from your M6. If it had dual stage tail with a "low" mode (200-300 lumens) in addition to the 900 lumen mode, I'd have bought one.