As pblanc said, strength is as much dependent on the layup and construction as it is on the type of cloth. In general usage a good quality Kevlar layup is no more delicate than a quality fiberglass layup. It can be much lighter to carry. In my usual reference hull, the 17'Wenonah Spirit; the lightest Kevlar layup is in the 40#range. The fiberglass hull using the same construction was around 50#. The less expensive layup in fiberglass was in the 65#range. Wenonah has used , different layups in this hull over the years. Core-stiffened, now called ultra-iight; cross-rib, center-rib,and extra-stiffened. They made all but extra-stiffened in both fiberglass and Kevlar. lots of different constructions and differing weights and strengths.
If you could lift it, the least expensive extra-stiffened fiberglass version was the most puncture resistant. It had so many layers of cloth in the hull bottom. I have paddled a cross-rib Kevlar hull for almost 30 years now and it has seen a lot of rough usage. The bottom of the bow has multiple repair areas of epoxy putty from rock impacts. The damage in all cases was just the gel-coat layer being gouged by the rock. The Kevlar cloth beneath has fuzzed from the impact, but never yielded. Several accidents have flexed the bottom so severely that two ribs have been separated from the hull. But the Kevlar hull has not torn or punctured, only the resin has cracked. All the accidents were repaired by securing the ribs with new layers of cloth and resin. This hull flexes under impact. Going over a submerged log you can see the bottom flex upward as the log passed under the canoe. It then returns to shape. The hull has many scratches from these encounters, but is intact. I can not say that this Kevlar hull is delicate. It is as strong as the fiberglass version of this layup, it is just more expensive and is 12# lighter.
Impacts are an "if" factor, portages are a reality. Never once have I wished I had bought the tuff-weave version instead of Kevlar. Several times at the top of the Raquette Falls Portage, I wished I had the ultra-light version,but never the royalex.
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