According to Woof's comments (he made the spreadsheet), Ostruppen currently have a permanent 50% accuracy modifier applied to each model. When in cover, they gain a 2-times accuracy modifier.
Kubelwagons are pretty strong if you keep them stationary like you'd do with an HMG right before an assault. Even with some focus fire, I my Rifleman can't help but get pinned before killing it.
Add Sturmpioneer or Volksgrenadier grenades into the mix and you've got a rather potent early game strat.
The most I can tell you to do is get an early Grenades Package upgrade. It costs 25 fuel, but it'll be well worth it. The M23 Smoke Rifle Grenade in particular will blind a vehicle if it's hit by it, keeping the weapons from shooting. Take that opportunity to get up close and turn it to scrap metal, or finish it off with a frag grenade (which takes off about half health, nice finisher if you're willing to use the munitions).
I've been toying around with the PTAD AT Bombing run in the CheatCommands mod.
And damn, it's pretty good. If you can land it on a tank (preferably a crippled tank), it will do some serious damage to it. I've seen it 1-shot Brummbars, Panthers, and Tigers on occasion. It will instantly remove half the health from a King Tiger.
Anti-infantry power is weak, but that's to be expected.
Airborne upgraded with anything (including the recently buffed 4x Thompsons) will tear through the enemy. Besides, the M1A1 Carbines that they tote off the bat are pretty good combined with the 6-man squad.
They're glorified Riflemen, sure, but they come with an extra man, the ability to be called in anywhere, reinforce from Beacons, and get Thompsons and M1919A6s. They're a match for any Axis infantry.