I apparently wrote this last winter (08/09) and forgot to post it. I thought it might be interesting so I am posting it now. We used it all last season and a few times this year too. It has worked out great and spending the extra cash on an awesome yoke was well worth it.
In the fall I put a canoe downstairs so I could do some work on it over the winter. We bought an Old Town Penobscot last summer for about $500 to use as our everyday (or everyweekend as it sometimes is) canoe to limit the wear and tear on our more expensive tripping boat. It was in good shape. There was some fixing up and changes I wanted to make to it. The wood seats and thwarts were a bit neglected but a sanding and refinish was all they needed.
The only change I wanted to make on it was to remove the center seat and put a yoke in. Some people would do the opposite, but we have solo canoes. A yoke allows the canoe to be carried comfortably by one person. Comfortable is relative. Portaging is never comfortable, but can be made less miserable. Flat yokes are a thwart that has a place for your neck. They are better then a regular thwart, but for long carries your shoulders start hurting fast.
There are different schools of thought on this and I have tried most of them. In the BWCA foam blocks that sit on the shoulders are popular. They are ugly, get dirty soggy with use. They work best when used with a flat yoke so there is more room for your neck. I am a believer in the Canadian school as far as yokes go. Take a big hunk of wood and sculpt it to fit nicely on the shoulders. They look beautiful. On our Swift Kipawa the best looking wood is the yoke. So after looking around for the perfect yoke I decided on a shadow yoke from SlipStream.