Plastic v Fibreglass

Among the many issues occupying my mind over the last year or so is what type of kayak to use ,fibreglass or plastic. The advantage of fibreglass is size. The biggest fibreglass boats are bigger than the plastic ones and as a largish size paddler I appreciate the extra load carrying capacity and stability. On the other hand, the upper river does have a few Class 1 and Class 2 rapids and plastic boats might be better, although I am told one can walk a boat through the rapids to minimise the risk of damage The other issue is cost with the fibreglass boat costing twice as much as a plastic one.
 I have thought of trying a 2 boat solution-i.e.buying a plastic boat for the upper river to Minneapolis and then trading it in on a fibreglasss boat when I get there. I regularly check the website of the store where I intend to buy the boat.and other gear. As far as plastic boats go, they sell Current Design Storms, which was the first boat I owned and which I used on the Hudson River a few years back. Cuurent Design also produce a wonderful looking fibreglass boat which looks as if it would be perfect for me and is the same size as my Paddling Perfection Seabear. I wish I could just take the Seabear with me