Totally subjective on my part from a slew of bikes I've had. My weight has varied the past 6-8 years from high 180's to low 200 lbs. Every SL bike under me will flex when I stand a pedal to the point of making the chain rub on the FD. Never had that issue with my TSX bikes. Some of my SL bikes have felt decidedly soft under me and seemed to sap my meager power when accelerating and my daily ride logs seemed to show that they were a tad slower. TSX bike were faster and the one Lemond was a marvel at how well it carried my speed and how well it would get back up to speed late in long rides when I'd get tired and lose focus a bit. To me I honestly would say I do feel a difference in the TSX bikes. Of course so many factors come into play but to me TSX isn't the "gimmick" mentioned above from my subjective experience. Can't speak to the 753 as I've never had a bike made from that. Hmmmm.....I should do something about that. LO!

Yet all that said above, I'm not convinced that any one type of steel tubing is inherently superior to the other. Application probably matters a whole lot more than anything when a quality bike is being built.