Hello, don’t know it this is mentioned before but, if multiple midi controllers could be assigned to multiple (vst) instruents it would be very awsome, expecially for live performances
Yes, it has been mentioned many times before 
And you are not the only one that find this usefull. And it would be even more important to have this freature the day renoise will support sysex 
You can even vote for this on the polls page if you are a registred user
http://www.renoise.com/comm_polls.php