you'll miss out on HEC-specific bonuses though, like the ammo regen and the increased movement speed (if spec'd into). but yeah, it can work. there are times when in huttball, i switch over to ion when carrying the ball then forget to switch back. only notice it when running alongside others and notice that they can keep up.
Huttball is pretty much the only time you'd want to run with ion cell. Except, perhaps, if you and a healer are outnumbered and trying to hold an objective. You can slap a guard on said healer, which should buy you more time for backup to arrive.