The goal is for a classical guitarist to feel at ease when playing the synth instrument.
I know about Yamaha and Roland models, but have no idea about their respective advantages...
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Godin and Carvin make affordable production model nylon-string "classical" guitars with a Roland-compatible 13-pin output that you can plug into a guitar-to-MIDI interface such as those made by Roland. You should also look at the computer-based interface called the StringPort, from Keith McMillan Instruments.