Hi ThatOlBluesSound,
Ive been using a fireface800 for my last few recordings, and am extremely happy with it, considering its price. Its a smart buy in my opinion. the Pres are very usable. I A/B'd them to my sytek pre's which are very clean also, and they weren't too far off. And the fireface conversion seems to be good enough for most mid level production. I dont have any simple acoustic samples right here, but you can check out a couple of recent songs done through the FF800 here:
Dalma Productions
(Listen to "Two Questions" and "Mirovia")
All of it was mixed and mastered ITB, no outboard except for the sytek pres.
Cheers