Later, when I was listening to the results, I noticed that the files recorded with the Microbook were full of clicks, pops and drop outs. I didn't hear any clicks during the recording process but that's the way the audio was recorded. I started to look for the mistake, changed settings and tried several things and finally found on a forum that someone simply suggested to exchange the USB cable. So I did that and it helped! But just a bit. Instead of a lot of clicks I just had a very few. I tried all the cables I had and could not find a real solution. So I have to send it back as it's simply not useable like this. I hope the guys from MOTU will solve this problem. I already used several interfaces with my (standard) macbook running Mac OS X 10.6.8 and never had this kind of problem. Anyway, here is a link to the files I recorded for the ones who are interested:
MOTU Microbook 2 vs. MOTU Traveler
Sound wise I like the Microbook - it sounds fresher and less muddy than the Traveler MKI, it has a strong preamp and a good noise floor. Hopefully the audio samples will give you an idea.
I have no time to waste and I want a new product to work properly, out of the box - and a USB cable of good quality but if MOTU solves this problem one day, this could be the portable interface of my choice. After this disappointing experience, I did not even check the on-board eq, compressor or analyzing tools. I can't rate this product, because it simply doesn't work.