ive been using traktor a lot recently and one nice feature in the midi section allows for "modifiers"
a modifier can be used to make one control output different results dependant on the state of the modifier.
for instance normaly Fader A controls Layer 1 opacity but when Button B is pressed ( turning the modifier on ) Fader A now controls Clip opacity.
using modifiers, you could essentialy program much more detailed midi mappings, but without the need to have a huge ( and expensive ) controller.... individual mapping for when you want fine control of a clips parameters, then just press a single button to switch to a mapping for general mixing of multiple layers, then press another single button to change to an effects specific mapping and so on....
traktor allows 8 modifiers, but any control can have 2 modifier conditions attached. for example Button A will only do something if BOTH modifier B and C are turned on... so with 2 modifiers, you have the potential for highly assignable midi control.
i hope that makes sense! i think something along those lines could be very useful in Avenue and realy allow people maximum flexibility from both the software and the controller they use.