4. Piezo vs. Magnetic
Though Roland's GK pickups are electromagnetic, most other GK-compatible guitars use piezoelectric pickup designs.
Both pickup types are versatile, allowing polyphonic output and switching between the direct guitar sound and the module sound. The two may also be blended to create interesting hybrid sounds - one easy way to make it sound as if your keyboardist is in perfect sync with your playing! One advantage of piezo designs is that they may also be wired for a pseudo-acoustic guitar sound directly from the pickup.