I think there is:
The SU-85 was actually about equal to the Stug III G in AP penetration and gun power although the (75mm /stuk L/48 still retains a a bit of an advantage at long range dueling -I forgot the exact engagement ranges that are usually given) and it allows the Russians to get 85mm guns before the T-34/85 cameout out. Remember the "85" was not too common until later in '44 and there were still alot of 76mm variants still hanging around until the end of ww2 contray to popular belief that they all magically turned into 85's on New years day 1944-lol. So it allows the 85mm to take to the battlefield from after September 1943-1945. Although it seems not too many people take too much care in placing tank loadouts on their maps.-
We really need the SU-152/ISU-152 and 122 for the Russians then for maps like Orel the Russians will have a tank capable of dealing with the German tanks and later the ISU-122 which was supposed to be lot more common than the IS-2 in terms of tank vs tank combat in the east which would be a nice change.
Im quite suprised that nonone actually attempted an RO "Expansion" mod that adds more much needed vehicles such as these. I mean for example if I wanted to make a 1941-1943 or even a 1944-1945 map without adding the same old tanks (for example nearly every tank map in Ro has a Tiger I, Panther G, and IS-2 tank ) or unhistorical ones to a map Im kind of out of luck the good people at the AHZ/captainO made a few 1941 vehicles but there are a lot of holes still that limit how much you can do with a pure tank map if you'd like to keep it somewhat historical.