Yeah our Wehrmacht buddies really need some love. Making infantry units skinnable (AND WORKING IN ONLINE MATCHES PLEASE) would fix the problem perfectly. Since that will probably never happen, they could just take the Volksgrenadiers' models (which are very nicely made and pretty historically accurate) and maybe give them to the Wehrmacht. To differentiate, tone the Wehrmacht's a more olive color (still accurate). I don't see a problem with letting some units in the same faction share models (like grenadiers and MG42 crew members), since the Western Front armies took this indiscretion a step further by letting some units even share the same portrait. The colored symbols will always let you know what is going on, so why not even mix some uniform models and camouflage patterns within units to make for an even more aesthetically pleasing game?
As for the big topic of Winter grenadiers, I've never seen those coats before, maybe they are from this picture:
I know a lot of guys in Stalingrad ended up getting civilian coats shipped to them or just stole some from the Soviet civilians and military, so maybe that's what Relic went for with the early-mid war German faction, since they do base a lot of their content on the Battle of Stalingrad.