I never understood why they didn't put the Ez8 instead of 76. But Rifle company isn't lacklust, just overshadowed by recon company. Cluster bomb >>> WP barrage while having a similar price and a bit longer time to drop. They are two fanstastic area denial but one far above the other.
IMO most of rifle company is more or less useless. Flamers are nice, but fire up is extremely situational and not that useful and flares are too expensive to be effectively used (and major recon is only like 15 muni more). The WP is good as well but the whole commander doesn't realy add much except the flamer.
Quite simply identical stats and cost. The only difference between the vehicles would be that the 75mm Sherman would have access to munition that increased its AI and the 76mm would have access to munition that increased its AT.
Then a player could choose between the 2 tanks on weather he need more AI or AT from his Shermans, and combine them with other units accordingly. For instance as 76mm would work better with a scott or dozer while a 75mm would work better with an M10.
Having another version of the 75mm sherman that is worse against tanks than the jackson but that can't kill infantry effectively is not that appealing IMO.