I use this now, but I also try to use it on some seriously old Dell laptops at my non-profit. Sadly, that means I must first install Ubuntu, vanilla. This means I then must login to Unity and install Gnome-Flashback.

Normally, this takes about 10 seconds on a modern machine. On these 10 year old Dells? Unity chugs... A task that should take me 5 minutes takes an hour because Unity lags so far behind the mouse and slows every single process on the machine to an absolute crawl.

I cussed out Canonical for this a few years ago when they asked me some survey questions. They wanted to know why Ubuntu was not more popular on the server. My answer was that Unity was such a crock of shit that no one wanted to go near damn thing, even if they were just going to make the machine into a headless server. It's that freakin' bad.

If the HW is the same, you could create a custom NixOS based desktop image based on Fluxbox (or awesome) with just the programs you need (1 browser, skype, mail program, etc.).

Then you can manage updates automatically, probably just security updates.

I imagine that can be painful.

I usually don't even bother doing that through Unity: just open a tty with crtl+alt+f6, install all the packages from there ;)

Even doing this is incredibly slow and laggy with Unity. Once you're in the shell, it's better, but switching is just super slow and painful.

What are the pros of Ubuntu in serverland over Debian?

sudo is pre-installed :-P

Seriously, none. I always go for debian, have worked on various ubuntu servers.. The only difference is that Debian is more barebones.