There is definitely a difference between the two types of resin- but there is no significant increase in abrasion resistance (the difference in hardness is insignificant compared to the hardness of the native rock). Epoxy resin (SR uses this) is much better for repairing boats as the bond to a dry surface is stronger. In laying up a new canoe there is considerable dissent, many consider the bonds across layers of wet polyester to be stronger than the epoxy bonds, others say epoxy is stronger period. I've repaired lots of boats and I have not noted much difference. I think epoxy is more sensitive to UV degradation-  SR hulls that have been stored in the sun suffer from delamination  and deformation over the course of a couple of seasons.   SR boats are less likely to puncture because the  cross rib lay up allows more flex than a foam core. There is a tradeoff- more flex means less efficient for paddling and a greater tendency for the hulls to deform  (I've seen lots of hulls with waves or bends). I've seen few large punctures in any composite canoes from flat water use- and composites are really easy to fix.