Makes no real difference which one you get, the M9 and the 92 are really the same gun except the 92 has a plastic guide rod and trigger. The M9A1, which is the new one, has a 1913 rail, different checkering on the front strap, a dual buffer recoil spring like the 90-two, other than that same as the M9. All the law enforcement package 92's are standard 92's with the plastic guide rod and trigger, they don't break or anything so I wouldn't worry about that. Just get whichever one you want, if you don't want to warning labels and you have to have one that says "M9" then I guess you know which one to get. My personal preference would be for either a new 90-two, which replaced the vertec in the product line or the M9A1, just a little bit nicer gun as far as features.
Oh yeah, I have a standard 92FS at home and it does great, my agency uses 92Vertecs, so I have shot a few different types of berettas over the years.