I mean the fact that I rather get double su76s than one su85 tells me there is something up with them. But I don't think we should take away the utility of the Su76. People seem to forget that players also rather get 2 or more stugs than a Panther. Stug is in the same boat when it comes to being too efficient.
Or are the su85 and panther too inefficient compared to their tier 3 counterparts?
Imo stug is clearly OP and Panther is clearly UP.
Imo SU-85 is hardly UP since it can hard counter Super heavies tanks with pop of 20+ while having a Pop of 12 (for the same role Panther has x1.5 pop at 18).
Su-76 on the other hand is very cost effective vs anything with armor up to a Tiger.
Imo stock TDs should be separated in "meduim TDs" designed to counter medium tanks and "heavy TDs" designed to counter "Super heavy" tanks while being less effective vs mediums.
That could be achieved with number of way like:
Medium Tds high chance to hit(vs super heavies) low chance to penetrate (vs super heavies)
Hevay Tds low chance to hit (vs mediums) high chance to penetrate (vs super heavies)
Target tables
Abilities designed to counter specific unit types.
In the case of SU-76 imo:
1) Increasing the XP value is a no brainier.
2) Making barrage a vet 1 ability help the unit be less spam-able for its barrage.
3) Reducing the penetration will make Su-85 a more attractive choice vs units like the Tiger.