Both stable and nightlies have been perfectly usable for S912 for a long time.
Try 9.2.3 stable and see what it does for you. It should be just fine.
Then try nightlies if you want to be at the cutting edge.
I personally run the nightlies and rarely have an issue but if you do find one, report it so that it can be fixed for the next release.
If in doubt then don’t forget that you can do a fresh install to an sd card/flash drive and test things from there without affecting your current setup.
There is no NG for the S912 and as has been said a few times, it may be a long time coming.