Dear Paul, great bike, great price point! When I was looking at similar bikes I have always seen them portrayed with small lithe people using them, as I'm 6' and 230lbs I was never convinced they would hold up under me. How noodly does the long stem feel? How much does the seatpost bend? You mentioned going with a sturdier stem, have you tried it? Is the hinge pivot gonna work loose, can it be adjusted?
About the disk brakes - my major worry has always been bending the rotors while traveling packed under everything else. I have had a downhill bike messed up by plane loaders before. Do you not have this concern?
Thanks!