How serious are these sync problems in your opinion?
In my opinion the Render Mesh modifiers trump live sync any day, as far as my testing showed as soon as I switched Cycles off and then on again the problem was solved? I'd prefer restarting Enscape for the times I'm editing blocks over not having edge softening at all. I'm also guessing this is a bug that the rhino team will try to squash and when that time comes Enscape is already ready to go?
We, at our office, use edge softening on a daily basis to get a decent level of realism without bulking up the model and destroying the Make2D capabilities for printing. This allows us to work on the same file for a much longer period without having to create break-off files for render, 2D work, and so on.