Features are nice but not a part of the core OS. I thibk you should count a non beta as when all planned core features have been added and it's expected to work for the end user. I remember the AOS4 pre-releases, and people where told that it wasn't completely stable. But if they where called "pre-releases" mainly because of politics, then we have a termenology problem.

First non beta should be core OS feature complete and expected to work.

As of AROS, I mentioned 1993 because talks started back then, but the first line of code was written and released in 1995. I meant it as an argument for AROS development started in 1995, and not 1993.