Biggest problem with E8 is, its a doctrinal solution to a problem that is not a problem because of stop options.
It is an alternative that doesn't bring much at the end.
It is debatable if a pair of E8s would be better then regular sherman and jackson combo.
Range increase will surely make it a bit more distinct, but I'm not sure if it'll be enough, given it probably would be selling point of the doctrine.
Depends what you mean by the 'problem' here. In 1v1, the main armour problem you're facing as USF is the P4. That's not because it's impossible to kill but because it's hard to for your tanks to push the flanks and force it away from your marauding infantry. The main value of the easy 8 for me is that you can build it as your second tank instead of a Jackson and force your opponent to invest in a Panther rather than a Brumbar or some other effective AI tank. A regular Sherman and Easy 8 will demolish double P4, especially if you get radio net online.
I don't think it's great to rush an Easy 8, since if your opponent just stalls for Panther you end up paying a premium for a tank with worse AI than the regular Sherman that comes out later. But if you build a regular Sherman first, your opponent is likely to build their P4, which isn't so strong as to completely nullify your Sherman and leaves them exposed to your Easy 8 timing push.