I’ve had an M-Box 2 Pro for about a year now. I’m a hobbyist and use it to record practice sessions on my guitar so that I can help myself get better (not sure it helps but hope springs eternal!). DigiDesign/M-Audio who is the manufacturer of the M-Box 2 Pro is very well know for the audio products and many professional and semi-professional artists use their products to record their music, podcasts, or other content. They also makes a leading software for audio recording professionals called Pro Tools. Pro Tools LE comes with the M-Box 2 Pro. The way that DigiDesign/M-Audio has designed their products is that they have replaced the default CoreAudio drivers on Apple’s OS X in order to run with their devices. I’m not sure the reason they do this but I’m sure they would say it ensures overall quality from end-to-end in recording audio. Another result though for the user is that it locks the user into a particular version of the operating system (for instance, DigiDesign/M-Audio claims that the latest version of the software only works with OS X 10.4.9). While I’m talking about OS X, similar restrictions do apply for the Windows side too. Also note that history has shown that DigiDesign/M-Audio is very slow to come out with drivers for newly released OS versions (they only just released Windows Vista updates, a year after Vista was released!).
With all, that in mind, I went out and purchased a product from Roland/Edirol called the FA-101 (very similar in specs though not identical). They seem to have a fairly strong reputation though maybe not as strong as DigiDesign/M-Audio for audio recording professionals. They don’t make any recording software though and instead work with other software manufacturers software. Roland/Edirol takes a different approach and makes their product work with Apple’s OS X standard CoreAudio driver so it works out of the box, no driver required. Windows requires a driver but they were among the first audio recording hardware manufacturers to produce Windows Vista drivers so they seem to be on top of things for their customers. When I got the FA-101 home, I plugged it in and it just worked with OS X 10.5 (Leopard) which was something that I could not get the M-Box 2 Pro to do.
I’m not sure that I am the right person to do an in depth analysis on overall audio quality for the recordings but from a usability point of view the FA-101 wins hands down.