I started my tandem riding as a stoker with ICS. Since then I have captained and stoked MTBs and road tandems with both types of drivetrains. I've found the ICS to be convenient for casual riding but prefer the conventional drivetrain for performance riding. We seriously considered and demoed a DaVinci before getting our Ventana.
If you're not sure which way to go it is an option to buy a conventional tandem and add IPS cranks, available through J and B Importers via your LBS. That way you're not locked into a DaVinci and you could buy a used bike.