Like you say, you are hitting 6,61A (would be interesting to hear if that is at the emitter btw). Most people will not see much above 6A at the emitter in a single cell single XM-L2 light, at least not for a long time. So Im not sure why you would speak or even mention 7-10A from a single cell as a theoretical high..
An XM-L2 should require about 4,2V @ 8A (reference). Even if you had absolutely zero voltage sag (not possible), and zero voltage sag due to resistance in springs, (not possible), you should never be able to get a theoretical high over 8A with a single XM-L2 and single 4,2V cell. Since batteries have voltage sag under load, and since a normal flashlight have a little bit of resistance we will always be looking and numbers well below 8A to an XM-L2. If you should be able to hit 7A at the emitter (something I have never seen with a single cell), then it will not be for long.. So again, 7-10A as a theoretical high makes no sense to me.... Makes even less sense to talk about 8-10A to an XM-L2 since it will not survive at those currents...
I guess theory is all relative.. or something like that...