i have plazma 2s, and nano tech 2s and 3s, my opinion on what i have,
hpi plazma's; great batteries, err, thats it really. charge great everytime and had them for around 2 years, top battery and although it seems expensive, it last well.
nano tech 2s; a good battery, used a few times now, about 9 months old. showing signs of puffing but still charging and working fine.
nano tech 3s; the same as the 2s cell really, decent enough battery although not used as many times as the 2s, but has been used harder lol, and also showing signs of puffing.
my verdict, although the plazma's are dearer, they seem better better value to me, plus they're hard case. but the nano's are good value batteries too. erm, i havn't helped, have i?
Scott