Like ImA4wheelr said. Parallel cells with not get you where you want to go. Unless you use a good bunch of cells LG D1 cells to power each emitter you will not see the emitter amps you desire. Even with those cells you will not see 6A+++ for that long (assuming you use lots of them)
Basically, you need to go with a buck driver.
Some useful threads:
High current drivers for single XM-L2
At what current do you kill LEDs - which driver was used?
The HX-1175B (Some know it as the Lustefire triple etc) seems to be one of the drivers that can do very high amps without issues. I might be doing a build using 3 of these at more than the 6,4A I down adjusted one to drive an XM-L2. Time will tell If I can pull it off and when emitters will die..
Like djozz said. Your main worry is probably the bond wires. Im skeptical that you will able to run it at higher than 9A even with your cooling. But I hope that you prove me wrong. J) Even 8A may not be reliable in the long rung.. who knows..
Another potential issue are current spikes from the driver circuit or whatever it is. The MF TR-3T6 driver seems to be killing emitters in the 6,5-7A range. Hopefully the HX-1175B will not have any signs of such behavior that might limit the peak amps where you kill emitters.
Lots of variables when going for the extreme. Be prepared to kill some emitters and find the limits of your own setup.. Maybe start with some cheaper XM-L2 T6 1A when finding the limits.. ;)
Either way, with low emitter temperatures you should see nicer figures than anyone else.
