That said, would I be hating life if I only owned a 4/3 and a 6/5/4?
I know that a 6/5/4 is overkill for MD/DE winters,
Yes you will be hating life only having a 4/3 and 6/5/4 on the Delmarva, and wasting money on unneeded rubber. You will be sweating your ass off in the 4/3 for over a month in both the spring and fall when the air is warm and the water is chilly and during summer when we have cool upwelling. And a good hooded 5 mil wetsuit is all you need for the winters on the Delmarva.