I had a Mackie Onyx 16 channel desk. It was ok. It was very stable as an interface, never let me down. I found with mackie that most of the gain in the pre is in the last 1/4 of the gain knob and they do have a tendancy to distort in this upper range. Not a transparent pre and not good for most ribbon mics either.
Having said that overall you could do alot worse and if used on louder sources should work out just fine.