The biggest issue that you'll run into when using Kevlar (same thing as Aramid) or Vectran is that they are lower density than the epoxy and tend to float rather than stay put. It is also much cheaper to use regular fiberglass materials and to put on a second layer if you need more strength or abrasion resistance, e.g. beaching the boat (yes, the Great Alaskan is designed to be beachable). The think the short and long of it is that you'll have a much much happier time building the boat using fiberglass than any other fiber and it exceeds the strength requirements as well (when built as specified). I know that while Kevlar/Aramid have excellent abrasion resistance, it also gets 'fuzzy' when abraded and that makes it absorb water. If the Kevlar is in between layers and your boat is used or stored in freezing temperatures, then the damp Kevlar can cause delamination when the water in it freezes.
That said, there is one application in the boat that I think can benefit from Aramid/Kevlar, and that would be to give the boat better puncture resistance, e.g. waves or swells dropping your hull onto a pointy wash rock for example. Since Kevlar floats in epoxy and is hard to 'fiberglass' with it, you would be best off vacuum bagging it if you use it. Another option is to use light (5-oz or lighter) Kevlar in one or more layers to build up the strength that you want. It's not too difficult to glass flat plywood with light Kevlar, without vacuum bagging, but curved surfaces are very difficult to glass without vacuum bagging (I tried). In any case, I'm rambling ...the usage that I was referring to would be on the interior of the boat where it's ultra-high tensile strength would be best utilized for preventing puncturing from an impact outside the boat. I would suggest glassing the forward half of the bottom panel pieces prior to laying them in the bottom panel molds and stitching them up ...while they are flat on the floor. I would pre-coat the plywood with 2 coats of epoxy, sand and wash, then apply one layer of 5-oz woven Kevlar, then put the bottom panels into their molds and proceed as usual (stitch, build the keel seam, add chine flats, fiberglass inside faces with glass as instructed etc.)
Just my 2-bits... I wouldn't mind hearing from others who've tried to use alternative materials and how it turned out for them.
Brian