me too use NiMH because easy to maintenance and saft on charging.
I bought few pack LiPO before, but all swallow-up after a period of not using, waste money ...
I think the rule of thumb for Lipo is do not over charge it and never let it drop the voltage below 3.2v.
Any C-hing can tell is it true? I always maintain my Lipo as I mention above, never have drama so far..(touch wood).