Interesting! I have several of those Li-ion batteries in LED bike lights. I tend to think they dont quite live up to their mAh rating so I'm interested to see what you find.
I successfully charge mine in series with my iCharger. I rigged up a balance connector that allows me to balance charge a 2s 2p pack. No issues other than you need to keep the charge rate low or they warm up. I'm sure you could do the same which would much simplify charging.