RE: LIFE battery charging in the plane question
I have not used A123's/LiFe batteries. I use Li Ion batteries in all my planes and charge them in the model with no problems. They don't have the same issues that LiPo's have.
Li Ions don't lose charge when not being used and they do not require balancing. If you want redundancy the 4 cell pack has this. It is basically 2 x 2 cell packs, if one cell fails it will not affect the other 2 cells. The 4 cell pack is charged through one charge lead.
I would not use anything else.