I do not have direct experience sailing either of these boats. I have, however inspected (for possible purchase) the C&C 29 and I have read quite a bit about the Beneteau as well as talked with one owner. I like both boats and would have considered owning either of them.
I own a '88 C&C 30 MkII just so you know my bias.
I think the constructions and materials of the C&C are superior to the beneteau. I prefer the keel stepped mast of the C&C to the deck stepped of the beneteau. The C&C is going to have an end-grain balsa cored deck vs. plywood for the Beneteau. C&C will have a lead keel. Not sure about the Beneteau but they are more of a production-line boat so Iron would not surprise me. The C&C is a few years older (early 80's vs. late 80's) but assuming similar condition, I'd take the C&C. One possibibility that exists with the benneteau and not the C&C is trailerability. If you get the shoal draft with the wing-keel, it is entirely doable assuming an appropriate tow-vehicle. I had a nice chat with a fellow from California who towed his Beneteay 28 to the Gulf Islands for the Summer.
Also look around for a Cal 28 or a Tartan T 2800. Or, more expensive $35-$40k US, A J28.
The prices you are seeing seem way high. I know things cost more in Canada. Why, I have no idea. If you extend your search to the US, you should see both boats, depending on condition, well under $30,000 US. I hope this helps. If you're from Great-Lakes Canada, there seems to be a lot in Michigan, Chicago, Ohio for sale.
C&C 30 MkII
Thanks much for this information, I appreciate it!
I would also love to hear from sailors who have sailing experience with these boats...