Thank you so much!
I wanted to do S21A into xhp50. It has shallow reflector, about 12mm so will be very floody, but there I can fit TIR from carclo so result is predictable (efficiency is so-so). Only drawback is lack of heat spreaders. KF8 looks quite good in this regard. I will also most likely try new S12 (21700 and 22mm driver) and put xhp50 there, but need to get some dimension info though.