Most GOTO mounts have some sort of pointing model. When you do a 1,2, or 3 star alignment of a mount, you are creating a simple pointing model. It does not require something like TPOINT for this issue to arise. Depending on the mount when you do a sync you may be changing the model (alignment). Thus the safest thing for SGP to do would be to avoid the sync. I too have good success with the current implementation. But, I suspect that if SGP calculated a delta RA/Dec and used that to slew that it would work equally as well without messing with the pointing model.
The way SGP works now is effectively a delta slew but it is using the mount's sync to calculate it.