Go, with either or both. I think the 40 is superior to the 9mm. I worked with a University police force, and we went from unarmed, (ASP), to armed, and went thru the whole debate and settled on the 40. Of course, being a very liberal school, we were accused of unnessary use of force. But all the research pointed to the 40. I carry all my Glocks in one zippered waist holster. Not sure of the name, but you just wear around your waist, and has a loop that you yank, and pistol is there. I've had it so long, forget the name. Anyway all my pistols will fit in one or other sized holster that are secured with velcro. Just my 2 Cents.