We had a blast writing some tunes with this unit and the clean signal was a joy to work with in Cakewalk. There are also several other settings in these screens that let you adjust the nuances of the sound. The manual is more of a reference. Finally, the only thing we found missing that would have been the icing on the cake is some sort of microphone placement modeling for the guitar and bass amplifier simulations. Some other units on the market provide you with the capability of adjusting where the microphone would be if you were miking the actual amp you are trying to simulate.
Common settings are head on, off axis, etc.
This feature may be something that's available in the higher end units of the line like the GM1000, but we haven't had the chance to get our hands on them yet. For a processor that offers so much functionality, the trick to getting the most out of the GM400 is getting comfortable with the interface and learning by experimentation. It's been my experience that getting the most out of such feature laden units as this is going to present you with some type of learning curve. The Oberheim GM400 had me scratching my head a few times in the first few hours I was playing with the unit. Some of the processes by which you back out of menus, change settings and save and exit can be a little confusing at first.