I've been very happy with LiFe and LiPo transmitter packs. I can't see myself going back to AA-sized NIMH batteries. The ability to go all day without charging once is great. Also, less weight.

I haven't tried the Nizn batteries, but I have a set on order.

As for as storage, I use my PL8 to take the packs to storage voltage after every session. I've never had one puff in storage.