I won't be using that head for that reason, it's probably fine with 3x 1W stars as specified for it, but 3x XM-L's will indeed turn it intoo stinky goo.
I'm slowly working something up that will take 3 emitters and heatsink properly. It's smaller too.
Battery box looks good though, and should take a Balance PCB without issue to minimise the need for opening it regularly.
Searching for the ever elusive Underground Titty Bar.
DDDWH CC