Pitch to midi guitar systems have been around since the mid 80s. If the OP only needs control data, there's no need to bring a dedicated computer and multiple channel sound card into the equation. I use a Shadow SH-075 which was built in W. Germany (!) in the late 80's I bought off of eBay and it's tracking speed is definitely acceptable, at least for what I do. There is a new guy on the block, the Fishman Tripleplay which I'd like to upgrade to as it's standard USB midi so will work with PdParty and my iPad. Both of these are relatively small as compared the Roland's rack mount and stomp box offerings (why don't they shrink the GR stuff by now?).