I personnaly use a laptop with a touch screen
(HP TM2)
It is good because you have direct access to all the functions by a finger click.
But in Live situation, there is some buttons, like fill ins, variations, start stop, call next registration... that you prefer to press on something real.

On my MIDI keyboard, I have buttons (pads) that I have assignated to my important live functions.

I also bought an apple wireless bluetooth keyboard, and put some stickers on the keys.

This is also good to control vArranger.
http://cs.gmu.edu/~sean/stuff/n800/keyboard/keyboard.jpg

Many options exists...Every one, his prefered way



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Regards,

Dan
http://www.varranger.fr