one of the first things that you may want to do is figure out if you want a touch screen or if you prefer "real" buttons... particularly for live situations "performance" there is something to be said for being able to feel your way around the interface. for anyone with a background with an acoustic instrument you know that you don't spend the entire time looking at your fingers and the keys, strings...
next is how many buttons do you need? there are a few other matrx style button controllers worth looking at. such as:http://www.lividinstruments.com/hardware_ohm64.phphttp://www.lividinstruments.com/hardware_block.php
as other have said; i wouldn't worry too much about actually programing any of these, there are a plenty of people online who would be willing to help you out with the various stages no matter which hardware interface you go with and i don't think it will take too long. + playing with new things is fun.
after years of "an apple multi-touch tablet is coming soon" unless it is magical like a bloody chitty chitty bang bang i am going to be underwhelmed.