For all who are wondering, I bought the cable and flashed the handset. Yes, you can run the mount with Stellarium. You have to download Stellarium Scope. You connect the mount with Stellarium Scope and then start Stellarium. The bad news: same clunky software. I see no difference in the software before and after the upgrade. Unfortunately, when it has been clear I have had outreach commitments so I have not tested the gotos. I suspect they won't be any better than before. I am used to my Nexstar 8SE. If I take my time and do a good alignment, my targets will be dead center in the eyepiece for hours. So, since the gotos in Stellarium are based on the alignment of the scope, they won't be any better.
I can't believe that they upgraded the software without fixing the glitches: Sagittarius is still Tagittarius. They still sell this mount with their other products. If anyone else has done this, I would be interested in your experience.
Would the GoTo++ function in APT fix this, because, as I understand it, it uses plate solving to find out where the scope is actually pointing vs supposed to be pointing, and corrects for it automatically?