Didn't realize that was an option. Do you have to swap any other parts or LED out of a stock M6LT to run these higher output batteries? I'll see if I get any bites on the 18650 carrier first.
26650 LiIon cells run at the same maximum voltage as the 18650 LiIon cells, hence they won't magically push any more current than what the M6LT driver electronics ask for. You're good to go with no additional modifications.