My worry with the 9mm is that due to the extreme short stroke of the slide, along with the slightly higher pressures of the 9mm (21,000psi vs 35,000psi), that the speed of the slide will be so great as to cause FTF problems in that gun. As we all know the .45acp has had its share of FTF problems. I saw no mention of added slide weight on the 9mm XD-S to slow it down. It certainly will be interesting to see. I don't want to be one of the Beta testers if you know what I mean.