Tell us more about the show...was OS4beta running natively on A4000...etc.?
Sorry, the A4000T was as 68040 as far as I know.
As most of us know, OS4 was developed largely on 680xx Amigas- that's what was running on Saturday, but it looks like its just a case of re-compiling the parts for PowerPC.
Its still nice to try it out and find it was as responsive as I remember 3.1 being on my A1200. I've got to get me one of these

It was certainly worth the trip for me.