Secondary stability is also a concern with a duck canoe in cold water. Primary stability can fool you, you think you are stable and then you go too far and wham, you're in the water.
A canoe with good secondary stability is safer from what I can tell. The explorer (not tryign to push them, but I've had good luck with mine) has okay primary stability but superb secondary stability. Once you get over the perception that it feels tippy and learn to trust the hull, it is a very good platform.
My only criticism with mine is that it is a bear to paddle solo without weight in it, for example fishing solo in a lake with any significant wind. It is a kevlar hull, so it is light, but it also gets blown around a lot. It paddles superbly with a slight load (2 paddlers++ or one paddler and duck gear).
I got mine in a divorce sale (was the husbands, sold off by the wife), so I got what I believe to be a fair deal. The kevlar hulls were pricey when new. Like Dave Park's shotgun buying advice, the trick for buying a small boat is to sock away some cash and start looking around. Eventually you'll see what you want and have the cash to make it happen.
There are about 100 canoes on the Burlington VT craigslist right now if there aren't many in RI. Might be worth a road trip if not for the price of gas. Take the family for a weekend trip, pick up a canoe for the ride home.
I'm not a fan of "dogs + canoes + cold water" personally. I know a good number of folks who are, but it isn't my thing.
Charlie