That depends on your personal definition of "tough as nails". Dynel has some good characteristics, and some that aren't very good for canoes, which is why it's rarely used on them. It does have excellent abrasion resistance (though not as good as Kevlar if the question is how much abrasion it takes to wear through it) but Dynel expands when resin-saturated and soaks up an awful lot of heavy, expensive epoxy. On a trailered boat like a Grand Laker, the weight probably doesn't matter much, where on a more typical canoe, it would be a major issue. Dynel also tends to be far more flexible than wood, so in most cases the wood remains the weak link on impact. The Dynel will simply flex past the point where the wood explodes, so while it may keep the boat from being holed all the way through, it won't prevent the wooden structure from being broken if you hit anything, or the hull from losing it's structural integrity. Like any exterior sheathing (glass, Kevlar, canvas, Dacron, etc.) the Dynel is not in a position to add much, if any, real impact strength to the equation. It is not in a position on the hull where its tensile strength can contribute, as the typical rock impact puts any of these coverings in compression, rather than in tension and the compressive forces need to be dealt with by what's on the inside of the hull (the wood) not by the exterior sheathing. On a stripper, we can increase the layup on the inside to increase impact strength (impacts put the outside layers in compression and the inner layers in tension, which is what these fabrics do best) but on a rib & plank boat it's still just the wood on the inside, and fiberglass, Kevlar, Dynel or other exterior coverings are all going to produce similar impact strength to the original canvas. In short, if you hit something hard enough to split a plank or crack a rib, it is still going to do so and your outer covering is not going to prevent that.
You can expect less abrasion damage in shallow water with Dynel if you can tolerate the additional weight it adds, and unless you really nail a rock, the actual repair is much more likely to amount to just touching up the filler coats of resin and the paint on top of the cloth, but understand that "strength" is a much more involved and complicated concept than it may at first seem to be, and adding a material which may be stronger or tougher than others in some ways, doesn't always yield an overall tougher boat. Everything is some sort of compromise.
