Just my personal experience. I've been running the enerG 4600 packs since they came out. They pull strong straight off the line and then smooth out at around the 2-3 minute mark with no degradation in lap times. (for me) Sometimes my fastest laps are in the last minute of the race. In comparison, I've run the Orion 3600 lipo. It never has the rip that the 4600s do and always feels smooth like it's at the 2-3 minute mark on my NiMh packs. I tried to add weights to the battery itself so that I could swap out a NiMh pack and put in the lipo with no effect on the handling. Unfortunately it doesn't quite work that well. No matter what I do, I have to make adjustments to the car when changing packs due to side to side balance on the track. I should have the new EA (SMC) 28c 4000 pack tomorrow, so I'll let you know if that proves to be better in the punch department.
Team EAM // Gravity RC