Nice ! I intented to do something like that but was too lazy ;-) Thanks for doing it and i hope you will forgive my "piggy-backing"

The two heads look very similar from the outside but when dismantled one can see some differences (beside the leds and associated gaskets) :

Pills differences:

  • Utorch pill length 11.5mm (left), S2+ pill length 13mm (right)
  • Flat front end for the S2+

Reflector differences :

  • Utorch reflector length 12.0mm (left), S2+ reflector length 11.6mm (right)
  • Utorch led hole 6.5mm, S2+ led hole 7.2mm

One more minor difference : Front O-ring is black for Utorch and Glow-green for S2+

About Utorch quality :

  • This is very subjective and i don't have any left with the original Black anodization but i didn't like it like very much ... up to the point that i baked one and sanded the other for a "worn tool" finish.
  • An other thing is that one had very gritty threads (ok after several screw_unscrew with added silicon grease)
  • The weakest point of the Utorch imho is the driver (no way to remove blinkies)