We had both SPARCstations and IBM RISC workstations running AIX. Our assignments were always graded on Solaris. But the IBMs had better keyboards, so I used those. The downside? I had a real knack for finding constructs that'd lead to a segfault in Solaris but not AIX.

I was too lazy to do things like shell into a remote Solaris machine to double check before submitting though. I was YOLOing before it was cool.