Like I have stated, Obers are completely fine as they are! However, the majority do have a point in saying Obers come out a little too late and reinforce a little too long, but that shouldn't be enough to dissuade them from getting Obers. Come out late? They are meant for late-game AI powerhouse, of course they gonna come out later! Reinforce too long? Then don't let them lose models! Keep them behind Volks (Powerful at long-range, remember?) and voila! But then Volks, they are being a little bit too durable for what they cost, especially the upgrade which makes little to no senses. Since Obers fight behind Volks, while don't give Volks more close-range DPS through upgrade so at least, they won't steal all of Obers' kills.
I think Volks are also fine atm, they are cheaper than riflemen and sections and hence don't do the job once those are vet three and have double upgrades is the reason to get Obers. Giving Volks very mixed weapon profile upgrades will make them useless I think.
Upgrades for riflemen, sections, guards are eqaully a no-brainer and in line with their overall range and mobility profile, they just scale better than Volks. The only mainline infantry they outscale are Conscripts without ppsh. But in Soviet matches most people play Penals and Guards these days anyway and they fully outclass Volks.