I have ridden my T2000 thousands of km's loaded and not loaded. You will never have a frame problem. This is one of the most solid touring bikes you will ride. My 2006 was ready to tour on right out of the box, just add a front rack and fenders and off you go.
Me + bike + load = 320 lb and not a problem, wheels are bomb proof.
You really have to test ride other bikes if you can, for me the T2000 was the right fit. You will likely wear out before the bike does.
There are lots of folks on the BF who tour on a Cannondale with good results. Happy touring!