@Nomander covered my thoughts on the subject better than I could have myself. Stats wise Aeon has a very good shield, especially once you factor in its build time. I could see a buff for another 0.1-0.5 radius, but moreso as a consistency fix than because it's underpowered.

Reworking it to a 2x2 structure with ED1 (or worse) stats would be interesting, but the balance implications of such a huge change are so massive that I don't feel confident theorizing whether it'd be a good idea without testing.