I gave up on that James, as it just isnt available on the market.. A computer with a 27" touchscreen is doing the job for me... everything nicely accessible over the huge screen..
.. It just doesnt have any hardware keys , knobs or sliders.. but nothing that cant be done with a masterkeyboard or an Akai MPC.

If you dont like a pc solution you could also try Receptor, which i hear a lot of possitive things about.. But then who am i kidding telling this to you, because you know ten times as much about the key market then i do..

But if you find the right sollution, please share it with us..