No, I completely understand what you’re saying. And even agree with you for 95% of it. Where we differ is who is responsible for keeping this “offset”. My argument is that it belongs in the ASCOM driver on in the mount. I’m not talking about slewing 60 degrees and ending up within 2 arcseconds, I think we can all agree that with the hardware we have today that will never be accurate no matter how it’s done. So for me the “long trip” ends up in the wash…it doesn’t matter, it will never be at subarcminute accuracy, and that’s ok!
The problematic piece is when you’re 1 arcminute away from your target and the software tells the mount its location the mount then ignores this as it believes it knows better, for what ever reason, then when the mount gets a slew it thinks it’s already there so it doesn’t bother moving.
If I were to hazard a guess I would assume that the mount doesn’t want to shift its model if a sync comes in which has an error < X arcminutes (maybe 2, 5, 10…who knows) from the mount’s current position. Effectively throwing away the sync as the mount says “Hey, I’m close enough”. Likely this is a hold over from when plate solving was less popular and iterative plate solving and centering wasn’t “a thing”.
So…all that to say yes it would be great if something held an offset (or whatever) it needs to accurately and precisely slew to a location when a small slew is issued. I just think that ‘thing’ should be the ASCOM driver or the actual mount hardware since they have all the information we have and SUBSTANTIALLY more about the pointing model.
Also having 1 thing control the actual pointing model is always preferred. Sharing this concern across multiple systems would not be great and could cause problems and creeping errors. I would think slews would actually tend to bounce back and forth.
However, I’m not against trying things out. So, below is a version of SGP that implement’s @freestar8n’s Sync/Slew offset which will NEVER sync the actual mount (keep that last part in mind, I would recommend performing a local sync initially or actually building a model otherwise your error will be fairly large and likely highly inaccurate!)
So if some folks could try this out and let me know how things work (with SGP logs) I would appreciate it. This BY NO MEANS indicates that this will make it into a release. This is just some experimentation
As I don’t believe this is even beta worthy at the moment I’m not going to bother even creating an installer. Just replace your “Sequence Generator.exe” with the one below (you should backup your old one and rename this one). Also don’t be too surprised if this fails completely, there has been about 2 minutes of testing with this, just enough to know it generally works with the sims.
https://dl.dropboxusercontent.com/u/25320932/Sequence%20Generator%20-%20Sync%20Offsets.exe
Have fun 
Jared