Here is a really nice guitar synth setup using the Analogue Systems rs35 module along with 5 other A.S. modules. The rs35 module does a remarkable job of turning the guitar's pitch into CV (control-voltage). There is no MIDI involved in this setup.
In 2008 Future Music interviewed Simon Lord (Black Ghost, Simian, Lord Skywave) in his studio in London and came across this very rare synth built by his father.