Which lipo to go with?

Would the hard case really help that much? I am looking to get 2 packs; they do not have to be the same either. Also would I see a performance difference between these?

http://www3.towerhobbies.com/cgi-bin...?&I=LXSRT6&P=7

http://www3.towerhobbies.com/cgi-bin...?&I=LXRWE2&P=7

http://www3.towerhobbies.com/cgi-bin...?&I=LXRWF7&P=7

The motor I am running says 45amps max.

Also, if I'm at the track and need to fast charge them, say at 2c(with the balancer) would it be ok? I an using the mrc 989 charger and it says 1.25c max charge rate for lipos, can that be overridden?

Thanks!