Ask if a 'solid' flywheel kit if available. If it is for a long term car/customer, it might be preferable and cheaper. Possibly slightly increased vibration at idle and might invalidate any related warranty. Has anyone had any problems with the sensor side of things? The 'dual-mass' reps at trade shows are reluctant to admit that their flywheels have a shorter life than a clutch plate. Check the archives - especially Dave McGee's 'fix'.