There are advantages and disadvantages to everything. But I hate dead weight so much that in some planes where there is little extra room and CG issues, I do the exact same thing you will do by using batts as ballast in sometimes inaccessible areas. I do have the ability to swap a pack out in 15 minutes though, if I chose, bc I built in a way to get at the packs but I'd hate to do it every time. It's so easy to charge in the jet if you set yourself up for success and that's easy. I have a long charge lead and balance lead that is zip tied together. I also zip tie the balance lead to the battery connector where it is easy to access in the jet to hook up for charging so there is no fussing for connectors. I hook up from the charger to the batteries and use a portable deep cycle battery as my field charger so it's no issue to charge at the plane, in the car, at the table, or anywhere else for that matter. Totally portable and not a pain at all. I've been charging Lipos since 2003 and Life and A123 are NOT Lipos. They are perfectly fine to charge in jets and do not represent a hazard during charge like Lipos do. The one thing I'd humbly recommend you do is to occasionally discharge and re charge the A123's or Life packs with a quality charger using a cycle function. It helps you know what the capacity of the packs are doing over time to make sure you don't have a battery problem. The charger will diagnose the pack when it cycles it if you have a good charger like a Revolectrix or what have you.