Since Surefire stresses that if one wants to use rechargeable cells in their lights, their LiFPO4 3.0v cells should be used, I would advise not to try using RCR cells. You can always be brave, bold, and foolish and try it, but I think you won't like the results. There probably won't be much of it, but if you watch closely I'm sure you will be able to see the little puff of Magic Blue Smoke escaping the first time you try it.
To my mind Surefire looked at the cell issue like this: At the time they were starting CR123A cells were a niche market used mainly for small cameras. They liked the energy density and decided to use them as their main power cell. AFAIK, at that time the rechargeable LiIon cell either didn't exist at all, or wasn't ready for prime time yet, so Primary Lithium was the way to go. Later on, when practical rechargeables started to appear, they posed two problems: 1) If used unprotected, one might be in the heat of pursuit/battle at the time the cells start to die, and try to eke out a little bit more before having to make time to change them. This usually resulted in the cells being drained too far and being damaged. 2) If protected cells were used to counter problem #1, when the cells got drained far enough the protection circuit would kick in and one would suddenly find oneself with NO light, rather than the dim light from an almost drained unprotected or primary cell. The third problem is the whole recharging issue itself - keeping track of cell pairs, the time it takes to recharge, how many to keep charged and on hand. Should primaries be carried as well as backup? If you are already carrying primaries as backup, why bother with rechargeables at all?