I like the Duty Officer (DOFF) system. My computer was out of commission, but my loyal DOFFs continued their assignments. Had a lot of dilithium and xp waiting for me when I logged back in. I've only lost one DOFF to a critical failure so far. Usually I get a Success or Critical Success. I've completed Tier 1 Diplo and Military and getting close on a couple of others. I should make Cmdr this evening. I've progressed through LCDR just using xp from the DOFF system. For someone that doesn't have a lot of time during the week, the DOFF system is a great way to continue advancing your character.
I've got green or better in all the space and ground positions. The DOFF I find most useful is the Projectile Weapons Officer.
I think that I have one of every career type, even the exotic ones like Medic and Flight Deck Officer.
I buy and sell a lot of DOFFs on the Exchange. Send me an ingame msg if you're looking for something specific. Jam@Rocketeer_7