Cybran is by far the worst faction in high level 1v1 right now, and giving them a nerf on top of that doesn't make any sense. I think any balance proposal or consideration must consider the faction in the context of overall balance, and this suggestion runs counter to that.
I am also against the idea of adding additional complexity to the game—which increases the already massive entry barrier this game already has. Generally, I think the best approach is to find the simplest approach that solves the problem. If the damage is OP, nerf it. If the AOE is op, nerf it. Don't just go introducing new mechanics to units, especially when solutions that don't require new mechanics work just as well, if not better.
I don't think the idea of having multiple damage rings serves any balance purpose or is intuitive at all, especially if the information is not clearly communicated to the player. I very recently (the past year) learned that nukes have 2 damage radii, that the targeting indicator actually shows that, and the outer radius does only 500 damage. I played Supcom when it came out in 2007 on and off until now, and I never noticed that in all my years of playing.