Would be interesting to see how much of a difference that makes when the case is clamped together firmly.
Problem is also, that there are FETs inside which have no direct contact to the case, just an indirect cooling path through the PCB.
If somebody tries that, it might also be a good idea to relocate the two capacitors that are inside the case (opposite to the two caps where the battery wires are) to the outside. They make direct contact with the FETs, so they heat up the FETs and vice versa, not good.
Edit:
Pictures of rcs2022 XL2:
http://www.rc-monster.com/forum/showthread.php?t=31997
Pictures of Revorocks XL2:
http://www.rc-monster.com/forum/showthread.php?t=31411
Pictures of my XL2:
http://s54.photobucket.com/user/liza...06/library/XL2