Just tried recording from my laptop's mic - the reported latency from Ardour was 5,3ms (with 256 samples/buffer). It crashed when I went down to 128 samples/buffer.
It has a jack and pulseaudio api wrapper. I use it because it means I don't need to muck around with configuring pulse and jack to work nicely together.
Is it comparable to jackd when used with something like Ardour?