The routing is very flexible for a unit of this size. I started the test by simply plugging the USB into the iPad. I wanted to create some quick sounds, so pulled up the KORG iElectribe. No problems there.
Next I added my iphone 4 to the line inputs on channel 1 and 2. Panned them left and right and played with some ambient/random noise out of RjDj. I recorded this to Stereo Track 1 in MT.
I then sent Stereo Track 1 back to the mixer so I could monitor while making some more noise. I then recorded Mono Track 1. Next, I wanted to play with the FX unit. The idea was to record a stereo effects track of Stereo track 1. It worked fine.
This opens up this unit to work as an effects processor for adding delay and reverb effects to tracks that have been recorded into MT. This is a nice feature for drum samples and guitars, etc.
On each channel you have the option of sending the source to the master out, aux, and effects bus. Through a switch on each channel you can assign a Rec option. This sends the signal to the USB record bus. The bus that actually gets sent to the USB interface is selected again with a button. By default it takes the master bus, but you can also set it to the Rec bus, and maybe even the Aux bus. On the return, these options allow you to send the effects signal back to the USB bus.
So how could this be used in real life?
You have a Drummer, Guitarist, bassist, Keyboardist, and Vocalist.
You send a stereo channel from the drums to ins 1 and 2, then guitar on channel 3 via the hi-Z option. Bass goes into channel 4, also with a Hi-Z option. The keyboard player takes the stereo input of 5&6. The vocalist needs to hold tight for a bit.
- First pass everyone plays together for the sake of timing, but only the drums are routed to the "Rec" bus.
- Second pass the bassist lays down a track.
- Third pass the Guitarist does his/her thing.
- Fourth time around the keyboard player gets it done.
- Lastly, the vocalist lays down a take or two in mono, with reverb in their ear, but not recorded.
After the 5 passes, we decide to send each track back out for some effects.
We record a delay on the guitar, some chorus on the bass, a nice plate on the drums, the synth is fine, but we do two effects passes for the vocals, one reverb/delay and one chorus.
We now have
6 stereo tracks (drums, drum plate, keyboard, guitar delay, vocal reverb, vocal delay)
4 mono tracks (guitar, bass, vocal, bass chorus)
Mix to taste.
Might take a bit of time, but I think you could get some very good quality recordings out of this. You could also expand the unit by plugging in external effects processors via the Aux out and the inputs of channel 5&6. Of course this adds bulk, bit the Mixer needs a power supply anyway, so why not add one more little effects box to open up options even more

Hope this quick review is helpful for anyone thinking about picking up thsi unit to go with their iPad and MT DAW.