Originally Posted by waynesulak

Largely this is a matter of preference but in my opinion Campy:

Handles front shifting much better. We can go from big ring to middle ring going uphill under full power while sitting. Also from middle to granny under almost full power. Really nice compared to our 12,000 miles with STI that required a pause in power to go to a smaller front ring.

Campy allows better front derailleur trimming

Campy fits my hands much better. Pure preference here but I spend a lot of time with my hands on those things.

For the weight weenie they are lighter.

For the non weight weenie - Until recently Shimano had those wires sticking out sideways which interfered with a front bag.

As a side note to me Shimano's big selling point is they come stock on almost all new tandems. Like Internet Explorer is installed with Windows so a lot people use it. It works ok so why change. I used the ones that came with our new tandem until the right shifter was worn out at 12,000 miles. When I had to spend my money I picked Campy.