The Duet is of course a fairly well thought of unit. I've been looking around a bit lately as I'm thinking of moving to a better and more portable recording set up. There are some other Duet-like tiny interfaces around. The MOTU (I think it is) has more I/O options than the Duet, including the option to connect another however many inputs via ADAT lightpipe. Whether that kind of thing's at all important to you is another matter. I've not gone too far into it yet as I'm still too broke to think about it too hard. Maybe the MOTU has more options, but the Duet is better quality (not necessarily the case, I'm just talking crap). In which case, if you don't need/want all those extra options, you'd probably be better off with the Duet.
Really, your first thing is to figure out what you really want from your interface. I/O, form factor, does it have to be USB bus powered, expandability, etc. And from there you can narrow it down and Google about and ask around for more specific info on each option. But there are a crap-tonne of interfaces around, and getting one endorsement from a forum user doesn't necessarily mean there aren't thousands of others complaining about problems they're having with the same unit.
