Unless you really need a bit faster servo speed or more torque there isn't much point in going to 5 cell packs. In most cases you won't notice much difference. You will also need a charger rthat is rated for 5 cell packs. If you just want more capacity you are better off getting higher capacity battery packs. 5 cell packs actully use up the power faster because you are using more current out of the batterys so you would have to go bigger to get the same number of flights out of the pack. Up to you of course.