I don't see how there will be any difference between a synced and unsycned environment in practice. You hit like a truck in i245, but your opponent has i245 HP as well, and vice versa. I think they will play out exactly the same, with very minor differences in practice.

If anything, an unsynced environment is likely to cause more complaints, because a fresh 60 in i195 dungeon gear is going to get destroyed by a i245 person and forget that their gear is at fault. At least with a sync, the gear ceiling is very low so time-to-kill metrics will be standardized for most players.

That said, I also wouldn't be too worried about them caving to complaints and diverting resources to 1v1 balance (which I agree doesn't matter very much). Just look at PotD, it can be entered solo but they have gone on record to say deal with it if your class isn't as good as others for soloing. A WAR, SCH, or SMN have a much easier time soloing things than most of the pure dps classes for instance, but you don't see them wasting energy trying to fix that.