About Guitar mode you can find more info at http://www.selskabsmusikeren.dk/index.php?option=com_content&task=view&id=241&Itemid=28 or http://www.rolandkeyboardclub.com/v/tips5.php or http://www.rolandkeyboardclub.com/v/prod_detail.php?id=218.

It's an easy and cool way to play guitar parts in realistic way.
You can use it for real time playing or for producing styles and songs.

I don't know how and when Roland will extend this technique to other instruments; I'm only guessing that they will do it since I see that they are working in this direction too.