I think the SST 40 is great for a triple or quad if you are after more power. The lower Vf of the SST 40 means each emitter gets more current. My triple SST 40 convoy L2 pulls 19A from an aspire 4300mAh 26650. A triple XPL V6 pulls only 12A with a 30Q. Other XPL and XML2 varieties pull even less current.
SST40 has an XML sized base. Not an XPG sized one like XPL or other common emitters.
This means that the SST40 might be a good choice for large triple emitter lights, but won’t fit in small single-cell Triples or Quads, because the standard stars and optics only accommodate XPG-sized emitters. An SST40 is too big to fit.