I mean you can nerf these but this should go hand in hand with buffs to the ATG.
Additional obstacle is that simple math á la "-20 far pen on Jackson, +20 far pen on ATG" does not work. But to be honest I'd leave it at that, I have actually talked too much about the Jackson again.
So back to topic:
Just judging from stats (I do not own the commander for the E8), I'd say the E8 lacks a role. Looks like it was supposed to be a anti medium tank brawler. It lacks the penetration against a Panther, even close range is unreliable. It just has quite a lot of armor, although even this is not enough to bounce Axis heavy AT, so it's also not really meant to soak up shots damage from these sources. The 76mm fulfills a similar anti medium role, but is more of a glass cannon approach compared to the E8. Given that USF lacks proper damage dealers against tanks apart from the (sorry) Jackson, the 76mm seems to work better in that regard. Also the switchable rounds let it scale against heavies.
> E8 should get 90% acc on move, not shitty 75% for it's price.
It can get +20 at close range for Cqc/ Diving attack as Med tank brawler. I also recommend E8 can have mark target ( + 10% dmg on enemy tank ) or passive effect from UKF Hammer tactic when radio net active. This changes could encourage USF Combine arm in theory.