MIDI NRPN Support
Right now you can link plugin controls, gain faders and some other stuff to MIDI CC messagges, pity that MIDI CC have a 7bit resolution, which means that for instance a 128dB dynamic range gain fader can be controlled via MIDI with steps of a whole 1dB at a time, not very suitable for real delicate and subtle changes.
Besides, think on this situation: you have a BIG midi setup with several MIDI controlled synths, effects and stuff you're recording on ardour controlling the whole with several MIDI surfaces, every CC parameter you bind to an ardour control on a channel is a CC/MIDI channel combination you will not be able to use on your MIDI chain, you don't want for instance midi control of master gain affecting modulation of your lead synth, do you?
Behringer (BCR2000, BCN44, BCF2000), Peavey (PC 1600x) and several other MIDI controllers support sending of NRPN MIDI messages, which can use 14bit resolution and there are hundreds to choose from, without having collisions with other equipment you could have on your MIDI chains.
It shouldn't be that difficult to implement NRPN MIDI support in ardour and IMHO I think it could be really valuable for using control surfaces.
greetings and a big HURRA to the ardour team for a wonderful job.