Though I lack a proper Unix power-beard, I think I reasonably qualify as an old Unix far. I got my start with SunOS 3 in college in 1987 as a user, and then branched into systems administration around '91. Back then I used and administered SunOS, HP-UX, Ultrix and IRIX (and Minix at home). I started using Linux in Nov '93. Professionally, I’m been primarily a Linux administrator since the early 2000s, with Solaris occasionally mixed in.
I work at Cisco and support Cisco Policy Suite, their PCRF product on LTE networks (which consists of RedHat VMs numbering between a dozen or up to several hundred VMs on a single node).