As it's been mentioned, I'd be curious to see if FRP were removed and only soft-retreat reinforcing were available (vCoH style playing ergo Forward HQ). Still keep the game the same way, with the USF ambu, OKW truck, Sov/Ost HT...just remove the ability for the "get out of jail" retreat card to be so close to the front.
If you do a hard retreat, that's part of the penalty for retreating, you go allll the way back to your base. Again, I think the early FRP of OKW makes them so powerful early game. They already have the strongest early game units (SP & Kubel combo), no sense it getting those back in action so quickly after a hard retreat. Give the other side a reward and time to breathe for forcing OKW back.
USF can only do FRP at T3 (Major). That's LATE game. OKW can FRP at T1. Slight difference. USF has ambulance at T1, but that's only for soft retreat, and it's weak as hell. When USF retreats it's blob, it goes back to base. OKW retreat it's blob, and it only goes back 1 sector (or whereever the truck is planted).
USF comes late, that's true, but it comes for free (if you decide to tech up) and is easily the best one, since you can just move the FRP once it's spotted - something that few players actually do, thus getting barraged to death pretty often. Brits and OKW don't have this luxury, their risk is greater.