Order them from one of the online shoe outfits that gives you free return shipping! Put on your loaded pack and take a long hike around the house (so they're still returnable) before you decide to keep them.

Do you have some running shoe stores in your area? That would be a better place to find what you need and get a proper fit.

Unless your feet never sweat, I don't recommend the GTX option. Your shoes will dry much faster (and they will get wet, believe me) without the Goretex. I just splash through fords and walk my shoes dry, although the process can be speeded by wringing out socks afterwards.