this is just an experiment. the biggest advantage of A123 is the charging ability. I can use 10A to charge the A123 and it will finish charging in 15-20 mins.
the disadvantage of A123 is its large size and weight. The A123 just fits under the body. Also I will have to add a lot of dead weight to the make it balance.
If your car can fit 1s Lipo (or 2s lipo), it is better because of the light weight and small size.
For t-bar cars, all 3 types of batteries can be used. but the issue will be how to balance the car.
For linked cars, only lipo or NiMh will fit. The round A123 will not fit under the shock. (unless they create flat A123 like lipo or you raise the shock)
So for me:
T-bar: 2xA123
Linked: NiMh
FYI: Westerners are racing with 1S lipo now. So this could be the new standard.