[suicideneil]

I think the OP needs a lesson in voltage here:

Nimh cell = 1.2v, 1.5v fully charged.
Lipo cell = 3.7v, 4.2v fully charged.
A123 cell = 3.3v, 3.65v fully charged.

Running a 3s2p A123 setup would be much slower than 12 nimh cells, about half the speed actually, just more punch off the line and better runtime probably.

if you are after ideas for battery upgrades, then I would say stick to either top quality nimhs from SPC or Promatch, or get a couple 2s 5000-8000mah 15-25c lipos from SPC (Im assuming limited budget here). A123s are nice batts with advantages and disadvantages, but to get their full potential you will need 10-12 of the buggers, which means alot of money, plus the charger for them also.