Could some of you Tandem Island owner's out there comment on how well (or poorly) the TI operates under solo, pedal-only power with the amas installed, either folded in or out.
IMO, pedaling the TI with full sail rigging is OK for maneuvering, but not practical for any distance. Speeds below about 3 MPH the turning is not particularly good and any wind exacerbates maneuverability problems. You would get better handling out of the front cockpit than the rear. It would probably be the slowest Hobie in that configuration.
Pedaling the TA (kayak only) is a different story. In smooth water, you should be able to do about 5 miles in an hour (solo) at a fast cruise, with good rudder authority and a nice ride from the front cockpit (with a well tuned Drive). The Adventure and Revo are still faster though. It would be roughly on par with the Oasis, but faster than the Revo 11, Outback, Outfitter, Sport or any inflatables (in approximate order).
Tandem, two reasonably fit guys can cover 6+ miles in an hour, making the TA the fastest Hobie kayak in the fleet. A TA co-ed crew won its class in the San Diego Bay 2 Bay race (5 mile version) a couple of years ago, also beating all other tandem SOT classes and all other Hobies.
It's a versatile boat when properly configured for its intended purpose.