I have been using 5s2p A123 in my X-Terminator, but I'm looking for a lighter weight setup. Which is why I chose the Maxamps 4s1p 5000mah pack. It's only a bit heavier than a 6cell NiMh pack :).
SH Z-Car, Custom Crawler, 8s Savage, 12s XTM XLB 1/7 buggy, 4wd 4-link rear/IFS Pro4 truck, Custom Hyper 10 Short Course, Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz