Apple A/UX always felt unfinished to me. Great leveraging the partnership with IBM, but IIRC some Mac apps would fail to run in some weird ways.
I played with it as a sysadmin at work, on a Mac IIfx with thousands of dollars of RAM installed.
Did you ever get to play with the Apple Network Server? A rebadged IBM/6000 box.
Apple's approach to distributed network services was really great...
Alas. This era was like the Xerox Alto -- visionary, but required $10,000 to run.