Sometimes people want unusual routings that are illegal in Sonar.
 
How about send and return plugins that would allow one to send a signal from anywhere in one FX bin to a return in any other FX bin, either in a track or buss.
 
This way one could do things like route from a buss to a track, split a track to another track or create delay FX with other FX in the delay loop or a variety of other things.
 
Obviously there needs to be at least a one sample delay, but additional "runaway feedback" protection could be built in fairly easily.