I found this reply from Neil shortly after I posted. Sounds like I haven't seen the subtle bugs in Start8 that are fixed in 10. There's also a few new minor features. https://forums.stardock.com/469388/get;3576926
I'm also curious about the differences. What changes (other than the app name) have been made between Start8 and Start10. I'm running Start8 on Windows 10 now and haven't run into anything obviously broken. I don't have a problem upgrading, but I'd like the developers to at least enumerate the differences.
I'd pretty much forgotten all about Multiplicity. I purchased the pro version coming on 3 years ago, basically because OS X support was promised as "coming soon". I do development on windows / mac, and I have both machines sitting next to each other. As a developer, I can understand the difficulties you must have encountered transitioning to xcode and working on getting a universal build done. I hope you get time to complete this task, until then I'll have to forget about this app a