Hi,
I tried a search in this forum and came up empty. If this topic has been covered before, I missed it.

Is the only benefit to charging above the 1c rate simply shorter charging times? I just bought a new charger that capable of charging at up to 20 amps. I have some 4700-5300 mah 70c 2cell packs that are rated at up to 2c charge rate.

Will they last longer if I stick to 1c charge rates?

Do packs somehow perform better if you really zap them, i.e. 3c and 4c charge rates, or do people do this simply to save time?