I like a backrest. Paddle all day and start doing a little fishing it's nice to ease back a bit.

I have used a crazy Creek for over a decade but it helps only very minimally. On the positive side it doesn't seem to interfere with good paddling.

I had decided to "upgrade" to a solid wood back/cane type seat and didn't like it. It did interfere with good paddling, plus it was heavy.

I see where Duluth Pack has come out with a seat modeled after the crazy creek. I will likely give it a shot. Perhaps it will be a bit beefier that the crazy creek but still have that flex that allows for good paddling. If I do spring for it I will likely sew some mesh type material in the spaces created by the straps (triangle open areas on each side)...........they strike me as an entanglement hazard especially if you have anything on your belt. 

I'm not familiar with the Duluth pack version, however, I do like the Sit-backer seat. It folds down for portaging, and is very comfy.

I know its not very common anymore, but if your an alluminum canoe guy interested in pure comfort bolt in a bass boat seat. It works great for base camping but obviously portaging gets even heavier. I have used it for a long time and dont mind the heavy weight for the extra comfort but i travel with my brother and we are young and athletes! ha. just an idea to throw out.

i have a lowe aluminum canoe and it has plastic seats with a bit of contour but no backs on them. the rear seat is close enough to the back of the canoe that i cut a piece of foam swimming noodle and stuck it on the crossbar behind the seat and did the same on the front seat. the foam sits just in the small of your back if you lean back(or sit toward the back of the seat), doesnt weigh much of anything, and doesnt interfere with paddling. it also helps to keep things cool instead of the aluminum getting burning hot in the sun. just a thought