Belt drive . . .
NO chain tattoo with belt drive?! We use the hot wax method to lubricate our chains and . . . suprise! . . . NO chain tattoo!
Weight savings? Have a tandem built without an eccentric (why not?) and you can save 4+ ounces of weight.
An eccentric is not really a necessity . . . as chain 'stretches' you can replace part of the old chain to take care of 'stretch' . . . repeat as needed.
Eventually, even with an eccentric, you will replace that cross-over chain.
Yes, Gates belt drive has the latest 'bling' effect.
Have ridden a prototype tandem with belt cross over drive several years ago (before Co-Mo did it). However the co$t of the custom chainrings/belt outweighed any advantages for us.
Just our input/opinion . . .
Pedal on!
Rudy and Kay/zonatandem