I have a 1.0 that was originally a 40. I have barrels in 9mm and 357 Sig that I would like to use in a different slide as the sights are slightly different between the 40 and 9mm/357 Sig. I would buy a 1.0 9mm slide if I could find one, but 2.0 seems to be the only type for sale. I guess I'd also get the bonus of reduced stretch and extra serrations if I use the 2.0 slide.