Not familiar with the Duette, but we bring our Tender Twin tandem stroller every trip, and we're glad every single time. Believe it or not, our tall 8 yo dd can still fit in that thing and fell asleep in it quite a few nights on our last trip. The Tender Twin breaks down pretty easily for a big stroller, not sure if the Duette does the same. Yes, the stroller has gotten a lot of use on those trips and it's starting to show, but the thing is a tank and just keeps going. We don't use stroller much at home any more, but the thing is great on vacation and we don't stress over the wear an tear. It was expensive, but you pay that much just so you can subject it to that heavy use and have it hold up, no?
Added.......
Yikes.....I see the Duette cost a wee bit more than even the expensive Tender Twin did back in the day. If it doesn't break down as easily as the Tender Twin maybe it isn't a great option to bring.