So I read this whole thread and the answer is . . . . . . . . ?
Well, I'll just summarize my own answers that I've followed for 40 years.
1. No matter what kind of water, tie in everything that can sink.
2. In whitewater or any swift current, tie in everything securely to the boat. No equipment on lines dragging through the water.
3. In quiet waters on windless days it may not matter much, but I still tie everything in, especially my main two main packs because they are buoyant. However, some draglines for smaller things are okay.
In all those years, I have never seen a boat-over-boat rescue executed or even attempted. Getting people and then boats to shore is what you do on a river. On a lake, a companion boat and swimmers can empty a canoe sufficiently without boat-over-boat, which is nigh impossible anyway if boats are full of gear. If solo, as I usually am, I'm not anymore capable of climbing back into my narrow solo boat, so I have to get it to shore, which means I will rarely go far from shore. Fortunately, I have never dumped in flat water.
Here's my current system with my Hemlock SRT:
You can see my painters of 1/4" floating rope, about 12'-15' long, loosely coiled under deck bungees. Easy to pull out when landing or if the boat were capsized.
The blue bag in the stern is my nine lb. chair, which is a big sinkable. Tied in at both ends, one end to a D-ring on the floor.
In the bow of the boat is another big sinkable, a canoe cart, which I actually rarely take on a trip. Tied in to a D-ring on the floor with its cam straps.
You can see my main pack, a Duluth (with a waterproof liner bag inside), is jammed under and attached to the thwart with one of its leather flap straps, easily releasable with one tug. Unseen under the map is my smaller waterproof day bag, also tied in. I want these two bags to be tied into the boat and not on draglines because, in a capsize, I want the packs to stay in the canoe to act as upward flotation to offset the sinking weight of the heavy chair and cart. In other words, I want the packs to assist the end flotation tanks.
Small dangling things are clipped to the front thwart or the inwale slots with cord and minibiners: sponge, towel, GPS, map case. Spare paddle is attached to thwart with a bungee and jammed into the bow.
That's everything for a trip of of two days or two weeks. Except my Panama straw hat seems to be under my adjustable kneeling bucket seat. It will attach to my head with a long leather chin strap with a slider knot. I can slide the knot under my chin if the wind picks up. Or, if I want some sun, I can slide the knot down to the end of the chin strap and flip my hat onto my back as Roy Rogers and Dale Evans used to do. Glasses are secured with a fabric Croakie to match my hatband.