IIRC Ubuntu Studio (and most (all?) professional linux audio systems) uses JACK rather than ASLA/Pulse like most other versions of Ubuntu.

JACK has a reputation for being fiddly to set up, but puts great emphasis on low-latency/real-time and other professional use-cases. I'd expect it to be competitive, but don't really have the knowledge to make the comparisons myself.

I did find this unfinished review of latency in JACK from a few years ago: http://apps.linuxaudio.org/wiki/jack_latency_tests#does_late...

I also would like to know your setup! I'd be very interested!

I was looking into whether I should purchase Windows or buy a Mac to run a DAW, but if you're saying that Ardour is good enough, then I can just install that this weekend!