I've had it on my SP6 for a couple weeks, but only because I'm in the slowest Insider Ring (was once called Release Preview, but I think they've renamed it.)
It has worked flawlessly for me, and I'm enjoying the new features.
I did note that 1903 was pushed to my older Asus T300 (hybrid tablet device similar to SP6) yesterday, and it's not an Insider device. Its specs are much lower than those of the SP6, but 1903 seems to run just fine.
I installed Win10 Pro 10 v.1903 a couple days ago by downloading the .ISO file and the update went smoothly. Just a few niggles now:
- Each time I boot into Windows, Comodo Firewall asks me to specify type of connection (Home, Work, Public). I suspect that a Comodo update will be needed to fix that.
- Can't get WiFi access within Windows Sandbox (see separate thread for that)
Other than those minor things, everything seems to work just fine on my SP6.