I don't know if it's possible with KSP's hardware, but I would like to have the option to set the knobs in controlmode from CC to NRPN.
Also it would be really cool if you could send userdefined Program Change messages per Track/Project in reference to the currently playing Track/Project.
I know this isn't something everyone needs, but it would be really nice to have some time in the future.
EDIT: I just found out that the KSP is already handling Program Change Messages, because it's reacting to both my Circuit and Circuit Monostation switching Patches/Sessions, though this is not customizable through the user, which forced me to disable send/receive on my devices for this kind of message.