I ended up going with the Kokatat Bahia PfD from MEC. Its $95 and its got the low profile back foam you need so it doesn't ride up on your back rest. Unfortunately they only come in Blue and Bright orange. The Blue ones go quick, they just got a new shipment in and they sell out pretty quickly in the S/M size. Otherwise you can go to Aquabatics across from COP and buy one of the NRS ones that have the same low profile foam back feature. They are a bit more, but are designed for fisherman, so they have pockets and neutral colours. I'm using mine on my pontoon for rowing. My normal wedge style paddling PfD has thick foam on the back and is super annoying and uncomfortable with a high back chair. Its too bad that the one from Bass Pro isn't available in Canada, it looked pretty good, but its not Canadian Approved.
http://www.mec.ca/product/5009-908/kokatat-bahia-pfd-unisex/?h=10+50004+50047&f=10+50004+50047