I can't comment much in comparison to GNU/LINUX for recording.

Nor have I recorded MIDI.

I have recorded audio.  NetBSD has a bit of a subtle gotcha: You
may need to run "audioctl -a" and "mixerctl -a" and twiddle some
knobs.  If you will be recording with audiorecord, and want to
adjust the sampling to 16 bits per sample (or something else),
you'll have to figure out an encoding to use, too; audiorecord
is unable to "just pick one".

This is all ~1-time work, however.  I know of no reason to expect
any long-term troubles as long as you don't keep changing audio
hardware or the like.

On one of my systems, in particular, I get a lot of noise (hiss/buzz
type).  That's a shame, since it's my main desktop box.  I assume
that it's caused by poorly shielded hardware.  I do better with
a couple of other machines, and have heard that USB audio devices
work well.

-- 
  "I probably don't know what I'm talking about."  http://www.olib.org/~rkr/