In my (probably only personal to me and therefore maybe not relevant for you -- sorry) opinion, the whole point of the XXX is that it's a bombproof plastic approximation of a squirt boat (I'm 175 pounds).  I can take it to the Nantahala and the Tuck, right out my back door, and squirt all the way down the river without worrying about cracking my ends if a spot's marginal or just too shallow.  I can't see any advantages (only disadvantages) to having a glass version.

If I were doing or paying for a glass lay-up, I'd just go with a real squirt boat.  The XXX is loads of fun but you can buy one for less than $300, and the $$$ you spend on glass could cover something custom-made for you.

Take care,
Mike