Certainly the eqmod - in certain modes - and the celestron mounts do have a problem converging with the current sgp implementation.
And the paramounts don't like to be sync'd in this manner - as I understand. So I guess they may work - but it alters the model or something.
I think g11/gemini has a similar issue? Not sure.
The two requirements of this sync/slew process are: 1) sync means one thing exactly - and often it doesn't. 2) slews will land exactly where they are aiming to land - and my mount doesn't do that - and I expect others don't also - because it is not trivial. It's not clear how many users have actually checked that a slew lands where it is supposed to - and the logs don't tell you if it did.
My question is - what is the reason not to use the method I propose. It adds a small amount of complexity on the sgp side - but sometimes that's what you need to do if you want to get the best out of a range of equipment with different behaviors. As opposed to stating rigid requirements on exactly what the mount should do when asked to do certain things - and saying if it doesn't behave as expected - it's the mount's fault.
Frank