I'm firmly in the "make weapon loadouts depend on the setting of the map" camp. Balance should be achieved through map design, including reinforcement numbers. Part of this is that weapons shouldn't be "mirrored". Just because one side has a certain type of weapon doesn't mean the other side should. I'm no historian, but I suspect that in a Stalingrad setting, the following would be true:
-Bolt action rifles as the work horse
-A fairly low proportion of semi-auto rifles. SVT-40 production had been down-prioritized in favour of the cheaper, more reliable and easier to use Mosin-Nagants. I don't know about the exact numbers of G41s, but I don't think they were produced in very large numbers.
-Higher proportions of SMGs and grenades than overall for the time, given the urban setting. Perhaps the default weapon on "small scale assault" type maps.
-Very few German hand-held anti armour weapons. Some Hafthohlladung mines (attached, not thrown). How many Soviet anti-tank rifles were captured and used by the Germans I have no idea.
-A problem with this is the lack of AT guns in HoS. I don't know if they could be included somehow, but I guess that's beyond the scope of this topic. (If I were to fantasize, I think it could be interesting if the defending team commander could choose setup points for AT guns at the start of the round, so that the attackers don't know without scouting where to expect them.)
-More "exotic" weapons like the MKb42 in extremely small numbers. Was the AVT even in production in January 1943?
-All in all this makes for a farily small pool of weapons to choose from, but I see this as a sacrifice to be made when deciding to focus on Stalingrad as a setting. I suspect we'll see a wider range of settings as time progresses, from community maps if nothing else. Maybe even panzerschrecks and lend-lease bazookas for the later stages of the war? Personally I really liked how Darkest Hour treated these weapons.
Of course, as always, realism is a fickle term. We do still want a fun game, which you hardly get by making it 100% realistic (as someone said somewhere, we don't want the game to delete itself if you die). Training and morale is pretty much impossible to simulate, I guess. Personally, I'm one of the people that feel RO1 managed this balance between realism and gaming better than anything else I've played.
As an aside, Anjelous, I believe you're talking about Lyes Krovy (Soviet trench assault with mostly SMGs) and Kurland Kessel (Karelia is the border area between Finland and Russia north of Leningrad, there was one user-made map I know of for RO 1, set during the Winter War).
