I for example have used 44.4 volts and was really happy. I also used 10S A123 and 10S TP with much enjoyment. My set up is: Schulze 40.160, Neu 1521/1Y. With the 1521/1Y I'm using 6S lipos. So you see, even though my controller can handle 14S lipos I can still use 6S. Now if I wanted more torque and run less AMPs all I have to do is throw my 1521/1.5Y and 10S lipos. The choices for motors and batteries in a HV system is more flexible then with a 6S system.
Another plus for using batteries with 2000-2500mah is that the cells are shorter and can be packaged easier, plus the a123 users would beifit in 10-14s 1p battery configurations, compared to 2p.