I don't think that adding more models to a unit will make the balance better.
IMO major balance issues at least for the Axis sides is the fact that the soviet units are so hard to annihilate, there will most of the time be at least a single man that will survive.
It's the same thing with Panzerfüsiliers, but it's the only German unit (together with Osttruppen) that have 6 men.
On the other hand every soviet unit (despite engineers) has 6 men.
6 men didn't feel like an advantage until infantrymen started constantly touching butts. I never went "OH MAN SOVIETS ARE SO MUCH TOUGHER" back when troops actually spread out and made their survivability against AoE barely any different. 6-man Maxims weren't impressively harder to wipe with a grenade (and then they go into light cover now and a rifle grenade can wipe them...) when everything was a lot harder to wipe with one grenade.
TL;DR I think your point is more FIX SQUAD FORMATIONS