Can a RC 7.2V 1300mAh Ni-Mh Pack be replaced by 6xAA 1300mAh Ni-MH in holder?
Probably.  The only thing you haven't mentioned yet is the internal impedance, or how much the voltage drops under load and then recovers when the load goes away.

I would expect that the RC pack would have lower impedance than the AA's, meaning that it's better at supporting high loads, but if the AA's work for you, then that's great!

Also, I would expect that the RC pack (at least a good one) would have its cells closely matched so that it doesn't unbalance itself as easily as a random collection of AA's would.  But if you charge the cells individually in a AA charger or use a balancer, that shouldn't be much of a problem either.