If I could get a pic from I Photo it would show a 2008 Matrix with 2 canoes on the roof, 2x2's extending the Yak rack. Tight space wise but it can be done by putting gear up inside the boats probably exceeding the load rating of the racks and roof creating dents where the feet of the rack rest on the roof. Gas mileage gets real lousy with two boats on board( have had as low as 375 km vs normal of 525 km per tank). Huge advantage of this wagon is that the hatch window opens separately from the hatch, really handy with boats on the roof. Love it but next one will be a Tacoma.
It was climbing out of a gully with my mom's 4x4 Pontiac Vibe (GM's matrix) that made me mention the 4x4 advantage for steep climbs. It's like having an "easy" button. Not a bad car for the money.
I have a front wheel drive 05 Vibe and I quite like it. The back was designed for carrying cargo and that was the main selling point for me (plus fuel economy) but the factory installed roof rack sucks. Drove up Red Squirrel Road with no difficulty earlier this year, but the drive into the parking lot at Ferguson Bay was rough. Some more ground clearance would have been nice. I hit bottom once or twice and I think I damaged my exhaust as I had to get it fixed when I got home. But your right about the effect of a canoe on top. A kayak is not bad as it's more streamlined, but a canoe is like driving with a drag chute out the back. Really sluggish.