IPS means that the faster cadence will see 100% of the work. Since the Captain is (usually) the more powerful rider they will be the one that powers the whole rig most of the time. That, and the other reasons given above, AND the fact that having another human onboard, one that does not have the intrinsic balance instinct that a sighted Stoker will have - these things make the tandem experience seem like more work than zipping around on the single bike. What should really be instructive is to take the tandem out without a Stoker. I still Captain my wife to her workplace on weekdays because she does not want to lose the fitness to do it when the jobsite opens back up. After she gets off and I turn around to head back home it's a different tandem! And my wife is strong. Very strong. But riding the tandem solo is still way easier and probably faster too but I haven't really measured.