This isn’t a full review but I very briefly had a KR1 with Osram W2 & another one with a SFN55.2 so I did some brief testing. You can see my full KR1 reviews here and here.
W2 has slightly more intensity and throw, but notice how much wider the SFT40 hotspot is and how the spill is noticeably brighter.
This emitter is not offered by Hank. I swapped it in as an experiment. You need a 3V driver plus the reflector and centering ring for GT-FC40. I don’t have beamshots (the beam profile is virtually identical to GT-FC40, but brighter and cool white) but I do have output tests & Sekonik readings.