According to this:
http://monster.traxxas.com/showthread.php?t=403550 the most you will get out of the 977 is 2.5amps, 3 if you are lucky. That is incredibly slow when you have high capacity batts. You will have them on charge for at LEAST 2 hours. with 6000mah cells. I own the 977, and I now think it was a waste of my money since it charges lipo so slow, and deosn't even tell you that until you buy it. The specs say adjsutable to 5amps, but when you do lipo it limits it to 2.5, which is pretty dumb. Anyhow, I use the accucell 6 now, cuz getting that was cheaper than getting 2 balancers for the MRC, and if I only want to charge one pack, I can still charge it at 5amps, it does both combined at 2.2 amps, or you can attach them in parrallel for 5amps on a 10000mah cell. Genereally charges in about 2 hours. Accucel 8 would have been better in hindsite, although any of the chargers at cheapbatterypacks.com are exceptional, and charge at fast rates, although they are more expensive than the other chargers. BUt, as you said, whats a hundred dollars on a $1200 truck.