Please forgive me if this is already described somewhere, but I didn't see it. With respect to the new Vendetta sizings, is the only difference between the sizes the length of the chain stay? If so, would it be possible to order one size and easily (or fairly easily) convert it to another size down the road (ie, by just ordering a new chainstay)?. I am presuming that the chainstay is an independent piece as it is on the Silvio. I ask because I hope to be a future Vendetta owner and am debating between medium and large. I am 6' with a 43.75 xseam, and it looks from the sizing chart that I fall a little more in the medium size. But John Tolhurst's blog article (which was very helpful) points out that the crank would be higher (and thus more aerodynamic) with the larger size. I'd hate to by one size and then wish later that I had gotten another.