I just got my XP-G R5 drop-in, 1.2A driver and 35x28mm reflectors from KD in last night. The 35x28mm reflectors from KD are a perfect fit for this light, the brass pill is identical to the one used on the 26.5mm R2 drop-ins so with this reflector you can just unscrew the R2 from the 26.5mm drop-in and screw it into the 35mm reflector, drop it in the light, tighten the bezel and turn it on and it works. Bezel closes all of the way with no problems and the reflector drops into the bezel just fine. Though I did modify the end of the case by beveling the edge so the 35mm reflector would slide in all of the way.
There are some differences in the refelctors of which I have three at this point that work in this light. I have the 35x35mm ones from DX, the 26.5x28mm and the 35x28mm reflector (from KD).
The 35x35mm from DX has the tightest beam with the smallest hotspot of the three, it has a very similar beam to the 26.5mmx28mm with the exception that there is a few inches less spill and the hotspot is a little tighter. The only problem with this one is it's too long so the bezel doesn't close all of the way (small gap) and it smashed in the tops of some of my alkaline cells slightly when I used it. I did take the UK SL4 with the 35x35mm reflector with me on a dive to 105fsw w/o any issues with the bezel not screwed all of the way down (less than 1/8" gap).
The 35mmx28mm reflector from KD has the worst focus of the three reflectors, it has a wider hotspot that is a little ringy and has a similar amount of spill to the 26.5mm reflector. Easiest to get to work though, just screw it on and drop it in.
I'll post some beamshots of the three in a few days, I just need to get some time to change the driver on my XP-G R5 drop-in. The XP-G R5 definately has more throw than the R2 drop-ins, the beam width is similar to the 26.5mm reflector but it has a much larger hotspot than the R2. I was shining them out my lanai at another building several hundred feet away to see the differences in throw. I don't really like all 5 modes from the driver it comes with, high is good, but medium and low seem too dim, strobe and S.O.S. I don't really like. The 1.2A driver I bought has 3-modes, high-med-low. Have yet to hook it up, but the XP-G R5 with the stock drop-in is probably driven around 700-800mA on high, so not as bright as it could be.
I've also got a UK mini-Q40 xenon that I've been modifying. I widened the inside of the head of the light so it could accept one of the brass pills with the driver and LED in it but had to grind down the pill to where it's almost tin-foil to get it to fit in so there won't be too much heat sinking from it. I also got a 24mm collimator that fits in it to use instead of a reflector. Will try it out with one of my R2s and post results. Not worried about leakage in the Q40 as I've already taken it down to 105fsw without issues with the original xenon bulb in it after shaving away some of the plastic casing so the LED pill would fit. I only really dive recreationally so 100fsw or so is probably about as deep as I ever really plan to go.
Beamshots and photos of all to follow--
