I bought the Olight M20 Titanium, which uses an SST-50, but returned it.
The LED was driven at 1.7 Amp, producing 250 lumen OTF. The light was overheating and after 10 minutes the output dropped further. The fact it is built of titanium added a further heatsinking problem, since titanium is a worst heat conductor than aluminium.
The driver also was not up tp the task, since it is loosing regulation around 4 V, when the 18650 has still plenty of energy. I believe this is due to the higher Vf of the SST-50 compared to a Cree R5.
The light was of excellent manufacture and had a really wonderful beam profile and LED tint, but I couldn't take the low efficiency and low luminous flux.
I believe that the current state of the art doesn't allow to built a typical 2x123 sized light using an SST-50 efficiently. A further step in progressing large junction LED efficiency is required. At 2.8 Amp current, an MC-E will literally outshine an SST-50.
The latest trend in LED development has accustomed all of us to very bright and easy to built flashlights because the LED manufacturers increased the flux by increasing the efficiency of the LEDs.
Luminus Device made very bright LEDs (I mean the SST-50 and SST-90) by working out some different parameters other than efficiency. As conseguence, their LEDs make a lot of light, but also a lot of heat; therefore, they aren't a direct swap in existing lights.
Lights using SST-50 and SST-90 needs to be MASSIVE, of which the Catapult and the SR-90 are a good example.
When designing a light around those LEDs, previously un-considered parameters, like the coating of the heatsinks, variability of heat conducibility of thermal grease, torque of screws, efficiency and designs of the converters, wire size and other obscure variables, suddenly become of utmost importance.
Conseguently, you need very skilled designers and/or a lot of trial-and-errors to produce a good and reliable light using Luminus Device LEDs.
The unspoken risk in this game is the fact that the other LED manufacturers may sooner or later achieve the same brightness increase Luminus Device did, by increasing the efficiency of their LED line, and not the LED die size and its thermal management.
In this case, we will find ourselves handling a number of club-resembling, heavy, expensive, power-hungry and obsolete flashlights - in almost no time.
Regards
Anthony