Sb is not alone in wanting limited use of sync. The use of sync is causing problems with several mounts for different reasons. You have already added a lot of functionality to make mounts center with accuracy beyond their native performance - and it just happens to use sync - but there is no need to. I would avoid syncing entirely in all sgp operations unless a user specifically requests it.
If this were a major change involving a lot of added state to track this would be a big deal. But I don't think it is. You can center without syncing and you can plate solve without syncing.
Frank