RE: Experience of using high LiPo charge rates
Over at RC Groups there's at lot of info on high charge rates. 5C is common and some people are even charging in the 10C region in accordance with manufacturer specs.
Parallel charging is also becoming common practice, If you have a high power charger like the Revoelectric PL8 you can charge 5S at up to 40 Amps. I typically charge a half dozen 5000mah batteries inparallel at about 25A. So I'm at a little less than 1C for each battery, but you can charge six batteries in about 45 minutes.