I have had this box for several weeks now (and an SK1since it came out) and the only problem I have had with the AM9 was a Tivimate update introduced a bug (after reverting Tivimate everything back to perfection).
Using Downloader and Aptoide TV I have been able to install every app I have wanted including Youtube ATV version, TizenTube, Syncler+, Kodi, Stremio, Tivimate, ImPlayer, Sparkle Player, Plex and SmartTube. All have worked as expected and Projectivy has worked using the settings toggle as you showed. I admit there may be problems with other apps I haven’t tried but those above should cover the vast majority of users of this site.
I look forward to you full review to see why you suggest holding off purchasing because I am at a total loss. The only downside I can think of for the AM9 is the lack of Dolby Vision.
Also, the SK1 with the S928 is more powerful than the S905x5 in the AM9. The S905x5 does have an edge in Ai processing power though. For most tasks the real-world difference is negligible and the other factors like OS version, 32/64 bit OS and memory differences also impact the “feel” of the devices depending on the user’s specific use. I wouldn’t recommend either for serious gamers because the SK1 is 32bit and the AM9 is weaker in processing power and only has 4gb of memory. Both are streaming beasts though. The Pro version of the AM9 will release later in the year and will have more memory so we will see how that helps its gaming.
I would recommend either the SK1 or AM9 to anyone looking for an AOSP streaming box.
One suggestion is that you should really spend a minute showing the built in ULauncher. I also use Projectivy but think you should at least show the capabilities of the built in launcher. It is pretty capable if you spend a little time customizing it and it is nice that Ugoos includes 2 different choices out of the box for those that don’t want to go third party.