The TR-J19 is an awesome choice for a few reasons. The reflector is HUGE. Beyond that, the emitter shelf itself is massive. The area where the emitters rest is thick, solid aluminum, and it screws with many threads into the body. It seems to manage heat well enough for a 3x MT-G2 with emitters pulling about 90W.
Really a ridiculous light. In the best way. Threads seem to speak good things about this driver for 3x XM-L’s, but I’ve also heard you can use the DRY driver with excellent results.