At 2200 lumens you’re looking at about 95 vs 89 lm/W for XHP35 (HD) vs SST-40 respectively. Boost drivers are great when they work as advertised, but based on recent tests the ones stepping up 1 cell to 12V seem to struggle. XHP35 HD and SST-40 have fairlly similar… relative or “optical” size I think the term is? The beam will be very close in profile: