Slightly used Record 10 Ergo off Ebay with a NOS Record 10 Triple found at BikeTiresDirect.com shifting 9 or 10 speed chains running on daVinci cranks with FSA chainrings.... works like a dream: always has, always will.

Only time it over or undershifts is when I forget to trim-in or trim-out the FD stop when I change from 9 to 10 speed chains... or when I just make a late shift into the granny ring with the drive chain under a lot of torque, e.g., operator error.

If there was a point to my post it's this: Trying to keep your tandem on the same bleeding edge of new single rider bike components can and usually is a PIA. It's been that way for a long time, and will likely remain so in the future.