Awesome. I only have the SST40 version, but I love it.
The XHP50.2 3V can draw well over 12 Amps, perhaps 15 (see HERE). Many cells will have quite a bit of voltage sag at such currents. The black Shockli 5500mAh 26650 is a great choice for balancing output with runtime, but some high-drain 21700’s, such as Samsung’s 30T or 40T, may provide slightly higher output at a reduced runtime.
Bear in mind, however, that this light has very low mass and heats up very quickly, thus dimming the output when temperature protection kicks in. This means that using the highest-output cells may be counterproductive. Bypassing the springs has a similarly limited payoff. The difference in initial output will be difficult to observe, so I recommend one of the black Shockli’s or the same OEM PLB-55A cell with other wrappers (see HERE or elsewhere in same thread) as the best all-around choice. It won’t be the brightest cell, but it will give longer turbo times and very good runtimes.
This emitter can consume everything this light can give it and then some. A “normal” cell simply runs it cooler for longer. More discussion can be found HERE.