I'd say it looks pretty good. Just a couple of things:
1. Never seen a spare wheel or spare track on a sherman turret roof. But I guess never say never.
2. I'm pretty sure most of the Operation Cobra M4A1 76w lacked the ventilation cowling on the rear of the turret. Others with more knowledge can chime in with that.
3. I think that ring on the turret side near the loaders hatch was a later feature as well. Again, not sure. Might want to search.
4. The hedgerom cutter. I know these were jury rigged on, but your design is one I've never seen anything close to in a photo. Many of the pieces are flat, and most I've seen were either made from L beams or I beams. They would pretty much need to be for strength, or else they would bend when they'd hit a hedgerow. However, there were MANY designs, so yours is not necessarily wrong. Just one I've never seen anything close to.
Hope this helps a bit. You've really done some nice work with the texturing, the clean built, the tracks (!), etc. Looking forward to seeing it done.
Rob