Just to add a bit to what M_M said about canoe lenght in solos. At some point more wetted surface has an effect on performance too.

The MII could have had some very soft bottoms?? Oil canning bottoms will feel like dogs.

Overall I'm a bit puzzled about the performance issues. There is too much hype about speed. Nobodies racing out there. Anyway in racing they say "If you're getting beat by minutes, paddle harder. If you're getting beat by seconds, try a new boat" Just another way of saying there's little difference between similar boat designs.