I was looking at the PT24/7 in .40 cal, and rented one to try when I was looking for my first carry gun. It was okay, but I wasn't too terribly thrilled about it either. I ended up doing some research, and decided to "settle" on a Smith and Wesson SW40VE. A lot of people bash on these guns, and from one standpoint, I can see why, but I also don't get the big hoopla at the same time. I hear the "they're junk" and "the trigger pull is too heavy." Junk -- absolutely not, I LOVE mine, and carry it daily, thus trusting my life to it. The trigger action IS heavy, it reminds me of my .357 King Cobra as far as pull weight, but that is EASILY modified, and my shot groupings got much better all around after doing the mod. I also own a Glock 35 that I carry some, but I just haven't shot it enough to be fully comfortable carrying it all the time. Out of the box, it is a FANTASTIC gun, ithas a long sight radius, allowing it to be more forgiving in the aim department, and the trigger pull is SUPER light, which, if you're careless even once, IS a safety issue. I believe it's rated from the factory at ~3.5lbs, and I don't dispute that at all. Opinions, are like assholes, we all have them, and they all stink but your own, and which gun to buy, shoot, and possibly carry is just that -- opinion.

As far as 9mm vs .40 or .357 SIG (very closely related calibers), well, again that's opinion, but I can give you some info. The 9mm is going to be a faster, smaller round, bar none, but if you ever plan on having to use it for defense, they are known at times to over penetrate, going right through the "target." Gene is right as far as hollow points helping to alleviate that, but that's apples to oranges, IMO. The .40 is going to a larger, slower moving round that is less likely to overpenetrate (that does NOT mean it can't won't happen, just reduces the chances) and there is going to be more tissue damage, thus dropping your subject faster. I'm all about consolidating calibers, so all my handguns, with the exception of the revolver I inherited from my father, are .40, and I love it. You get CLOSE to the knockdown power of a .45 with a good bit less recoil. Comparing it to the 9mm, there is going to be SLIGHTLY more recoil, and it's going to have a "snappier" feel to it. Hopefully that helps you out some. If you have any questions, I as well as other wil do our best to help you out.