I have a Powertap (that doesn't see much use these days) and a Quarq/705 setup for my single bikes.

One problem with riding the tandem a lot, without a power meter is that it throws off tracking the cummulative matrices in Cycling Peaks. Hence, I would love a power meter that gives the power for both riders on the Tandem.

We thought about the I Bike, but in addition to the setup, and extrapolation issues, it wouldn't solve my problem of getting the Captain's only power.

Perhaps a Quarq for the captain, and a I bike? You'd need a crank, with a removable spider. I don't see an intrinsic reason you couldn't run an FSA Team issue, set up backwards, with some locktite on the pedal threads.

Also, there was a guy on here that had a tandem set up with dual SRM's. Rather pricey, but it was for a study presumably supported by a grant.