I threw caution to the wind and upgraded my iPad to iOS11 beta and then downloaded Procreate 4 beta. Both work beautifully and Procreate 4 has some nice new features. No major bugs that I've seen, and I still have Procreate 3 and can use that if I have to. So far I haven't. So it's been good for me and I can recommend it, but be sure to do a manual backup to your computer first to be safe.