Christian Henson recommends heavily the use of Expression and Dynamic controls to make instruments more real. However, I believe his approach is fundamentally flawed in using hand faders which Midi controller keyboards rarely have a full set or can be extended to provide expression, dynamic, sustain in all its glory in the majority of offered keyboards. Using hand controllers means you become a one handed keyboard player.
I have stumbled across Audiofront who make midi expression controller where you can plug up to 4 expression/switch pedals and therefore for my use with BBC SO Pro I can use 2 Roland EV-5 expression pedals to control expression and dynamic with my feet as opposed to Christian and his fingers.
Does anyone use foot midi controllers like this?