Honestly i would prefer to see entire Armour Company as another Tech for USF with some additional arty unit.
Only chance to make m10 working again is to move them to T0 and make it accessable after teching T1 and T2.
Armor Company is probably the commander most in need of fixing.
In addition to making the M10 a call-in, after T1 & T2, I'd like to see the following changes:
1) Make it self-spotting - the open turret meant that its sight would have been as good as anything else in the game.
2) As a counter to making it self-spotting, make it suffer a main gun crit when taking damage from mortars, grenades, or any type of arty. (self-spotting would make it OP otherwise).
3) Allow a MG upgrade, which the real M10 had as an option.
4) Give it a 100 range, 35 muni barrage ability. M10's were often used as mobile arty.
Other changes:
Either give assault engineers a better base RA, or make them a 5-man squad at the same price, and standardize the reinforce cost to something like 26 mp.
Replace the 240mm arty with the old 180mm arty from Mechanized. It rarely hits, but hits too hard when it does.
Replace the elite crew upgrade with just about anything, but preferably a Pershing. If replaced with a Pershing, make the Pershing buildable from T3 and not a call-in. The Pershing would need to be reworked, as it is overpriced and badly underperforms in team games. If not a Pershing, then replace the elite crew upgrade with Easy 8's, which are currently okay for their cost.
Tactical Support Company also needs remaking. The Calliope was badly overnerfed. It doesn't do anything well. The cooldown is too long for it to work as a good area denial unit, and all three barrages don't do enough damage to make it effective versus OKW trucks.
The P47 strafe is a joke. It should be replaced with the P47 loiter, which should also have its price reduced. Along the same line, the P47 recon seems pointless, as it isn't that much different than the major's recon.