There is not any modification that I know of to help you with your streamlight m3. Part of the reason the M3 is out dated is because as you say "I'm tired of popping those little bulbs!."
If you're on a budget try maybe a TLR-1, if you can afford it though the Surefire x300 is the one to get. Switching will be slightly different than your m3 though on the surefire. Either will outperform your m3 in runtime and brightness.
I think its more a lack in interest in the m3 than anything else in regard to why you haven't got any replies so far :sweat:
If you are really keen to do it I am sure there are modders on cpf that could do a stellar job on it. Don't know who, and how difficult it would be to do. You've got to do a cost benefit analysis though as to improving what you have and buying a new light ...
I am not sure what use your m3 is for, but if you are looking for holster commonality I think ( double check this, I haven't tried personally) that the TLR1 will fit in holsters designed for the m3. I THINK don't hold me to that