Last Dec, I put in my back order for both the 40 and the 9. I decided that whichever one came in first would be the one I bought. The 40 came in and that is how I got into that caliber.
I love my 40 and love the way it fires especially after doing an Apex trigger mod -- but I am intrigued about being able to convert it to a 9 with just a barrel and mags. I may do that, but then on second thought ........ why? This is my EDC gun and I kind of like the idea of having a wee bit more punch. My home-defense weapon (in my bedroom) is my M&P FS 9, outfitted with laser/light, tritium sights, and also the trigger mod. In the middle of the night, I like the idea of having 17+1 rounds before even thinking about having to go to another mag. The chances of someone breaking in on me (with my two watchdogs) are next to nil --- but sometimes NIL happens, and I pitty the poor schmuck who tries it.