The latest Classic version have been installed onto an Amiga4000 (mine), and was also available on an A1K2 at AmiCon a few weeks ago.
And it´s good, really good. I have no OS3.9 on my A4K since then.
My fav demo runs as hell on it, much faster than on a 060 under 3.9 (Respirator Stories).
I have no time to set up and install everything what i use daily, but sooner or later it will cover all my needs as OS3.9 did it before OS4.
Regards,
Reynolds