Since the last few patches I find the PPSh handles much more easily than it did during beta and first release. Maybe they haven't changed anything and it's a placebo effect....but I'm finding it doesn't kick like a mule so much anymore.
I'll also say, if you want to see the Russians kick ***, Ducksoup Seattle is where you'll see it happen. The best players go Russian and I've watched them steamroll Germans on every map from Commissar's to Fallen Fighters.
I think it's just that, all other things being equal, it's easier for German players to mount a sloppy defense/offense than it is for the Russians. The MG34 is formidable compared to the DP-28, pretty much on every metric. The lower rate of recoil on their SMGs/auto rifles makes for more comfortable solo play.
When the quality level of players on each team is balanced, it's non-issue mostly and the a-symmetric balance works. When there's even a slight imbalance in the teams though....I think you feel it more as Russians. Especially when its compounded by stuff like, a German MG team that knows what they're doing on Pavlov's. A pair of quality German MGers can be worth more on that map than half the riflemen on the team.