Originally Posted by
DCwom
.....The reason? The Da Vinci really only lets one or the other rider coast, its not like you can have a different cadence, for us it wasn't worth the extra complexity (and $) in the drive train. .......
You actually can achieve different cadences although the ratio will be fixed. The captain can run a different sized timing chainring from the stoker timing chainring. If the captain like to spin and the stoker mashes, run the stoker chainring larger than the captain, or vice versa.
I agree with everything else, they are great for mismatched teams and if you need superwide gear ranges. As for added complexity, I would have no reservations touring with the jack gear.