Why would you buy a new bike? Yours would fit the demands of the ride perfect, assuming it is in good working order you should have no concerns of durability. If you want to make it a little more comfortable you can always just fit wider and more durable tires. One thing I would consider, if you have some superlight high $$ race wheels on there you can build a simple and durable wheelset for the tour like open pro/ultegra combo but if you have the stock wheels they are more than capable of doing this ride, then some.