That's a shame, my digilight ones unscrew which is mighty handy.
I have just got myself a M900a clone for my RAP4 paintball marker. The head looks externally like an M3, but inside the lamp and reflector assembly are different. Basically what the manufacturers have done is make a new, bigger reflector that takes a G90 style bulb screwed into it. The thing is I'd like a HOLA for it. Currently I'm using one of my digilight 9v lamps in it, which is an improvement over the unidentified lamp that came with it, but it's still only 105 lumens.
I could possibly drill out the hole in the reflector and use an MN11, but focusing could be an issue, and once I've drilled that hole there's no going back!
And before anyone gets on their high horse about buying clones and getting what I paid for, yes you are correct, but I can't justify a real M900a for what is a game/sport.