Or one battery, freeing them up to use a Heavy slot for anything they want.
Fringe seem super good because (as far as I can tell) every build needs a power plant, but the other race items are things it's possible to get by without. Like, a Fringe with a missile seems equivalent to a Brunt in all respects other than stats. The Fringe can easily swap out the missile, though. Not sure how to play without a heavy power plant.