I have restored a Data General MicroNOVA that also uses octal. It has an emulated front panel over serial and uses octal in multi-digit commands like specifying which address you want to boot from, "33L" to book from an MFM disk controller for example. That is probably a legacy carryover from the NOVA 3 and earlier where you would be able to input the same thing into the front panel switches.
Fundamentally I wouldn't say octal is fundamentally easier to interpret other than hex because it's just half as many digits. The shorthand things about octal used in unix you mentioned all still technically apply to hex as well. The only really tricky part is where it becomes letters and you have to think if D or E is the odd value with the first bit set. If you were doing hex all day though, the 6 hex letter patterns would be pretty easy to memorize.
Personally I would say for front panel systems specifically was just about physical space for the switches. If you look up CPU trainers for something like Intel 8080 in the Altair 8800, you'll see it uses a hex keypad. Multiple 16b values would have been a lot harder to fit in single bit switches.
Fundamentally I wouldn't say octal is fundamentally easier to interpret other than hex because it's just half as many digits. The shorthand things about octal used in unix you mentioned all still technically apply to hex as well. The only really tricky part is where it becomes letters and you have to think if D or E is the odd value with the first bit set. If you were doing hex all day though, the 6 hex letter patterns would be pretty easy to memorize.
Personally I would say for front panel systems specifically was just about physical space for the switches. If you look up CPU trainers for something like Intel 8080 in the Altair 8800, you'll see it uses a hex keypad. Multiple 16b values would have been a lot harder to fit in single bit switches.