I'm telepathic, and can still answer your original post...

MRT do not copy your number for anyone else other than you, as to MyLaps system, it's all very nice but I suspect the way they have now done it comes down to how your race software uses that new sub number.

I like the idea of one number myself, the Pure RC4 I ordered is a sub number off my original Hybrid.

Two things bug me with transponders, one if everyone lends them to friends etc, then somewhere along the way you get timing issues cause that number stayed in the system, and two is I have yet to be able to test my new RC4 cause it keep raining here...