If you look in my table - SU-76 still misses to axis mediums and don't ahve 100% chance to pen, while Stug always hit and always pen. And if you told about such "unusual strat", you can do the same witk OKW or even with OST (spam of mg-42 with pgresn with shrecks). Or 222 spam. 2 222 can kill 1 t-70 if you have enough micro to block his back.
I repeat again, if you trying compare stug and su-76 - result ALWAYS will be on stug side. SU-76 NEED changing of it role, NOT to be "soviet stug". SU have it's own hardcounter TD in T4. No need make 2 when 1 is enough.
Su-76 and Stug-G should have around the same accuracy at the same range.
While the Sherman have target size 23, PzIV/T-34/76 22 and Cromwell 20. I doubt that Stug-G has any meaningful advantage in accuracy over the SU-76. Even if it does its gone by vet 2 which SU-76 can reach allot faster.
(have you updated your numbers to the latest patch?)
And once more Stug is more expensive vehicles fight cheaper vehicles with the added utility of barrages and that makes SU-76 cost efficient by comparison.