Given that every time we fly with a tandem, I have to break and reassemble the drive chain at least twice. Timing chain I can de-rail so I don't normally have to break it for travelling. If special one use connectors are required every time plus a special tool, the attractiveness of 11 speed does diminish a bit. In addition, Masterlink (or similar) quick disconnects are great for on the road repairs.

Sheldon's comment on chains

Are narrower chains just as reliable as their wider cousins?