Six years after receiving my Surefire 6P (incan) as a gift I think I might have finally made it almost useful!
For me initially it seemed bright but the batteries were expensive so when they were depleted I just put this light in a drawer and forgot about it. When I later got into flashlights somewhat I pulled it back out and replaced the batteries but it only had one mode and with the incan drop-in it no longer seemed bright and it had artifacts in the beam.
When the XM-L’s came out I decided to get a single mode drop-in for the Surefire. It was brighter but I still didn’t like having to buy CR123’s so I didn’t really use it much. I put a piece of diffusion film over the lens to make an already good beam even better.
Today I received my first pair of rechargeable CR123’s just so I could actually get some use out of that light. If anything it’s even brighter on those batteries. This light is still kind of a one trick pony but I think it’s finally useful and I may use it for other things in addition to an emergency light in my nightstand.
That’s a lot of work to make a light useful however. It seems like a flashlight should be useful out of the box 
If I decide I want an incan beam sometime I can’t use the original bulb with the RCR’s so I’ve got a compatible incan drop-in on order from DX. Surefire is good at one thing…tying you to their batteries!
I have a XP-G R5 3 mode in a P60 clone using 18650. The XM-L is fine as well as it’s only driven at 1.4A.
What I need are some dogs