In my case I am using EdgeHD11 at f/10 with 8300 ccd and 0.4" per pixel. The guide camera is a qhy5iii-174, which is fairly large and sensitive, and I am guiding with MetaGuide. For optimal framing I may need to put the guidestar somewhat close to the edge - and it may move off during autofocus or pull another one in. If it happens to be well centered and there are no other guidestars around then it is less of an issue.
I have let it run, doing automatic autofocus periodically while I sleep, with exposures up to 30 minutes - and it has worked well. It is doing all this stuff about unlocking the guidestar and stopping guiding - then running autofocus - then re-locking the guidestar and starting guiding - and it works well.
But sometimes another star does creep in and things go wrong.
So although this is a fairly challenging imaging situation - the equipment isn't the limiting factor since it is mechanically capable of centering on the arc-second scale - and the autofocus gives very repeatable curves. The main thing I need is accurate software centering so the guidestar lands where it should be and the framing doesn't change during an imaging session. If I had that and a check on the framing after autofocus - it should all work much more reliably.
Frank