I like my 9mm as it was easy to shoot and the ammo were priced ok. I owned and shot a 9mm for the first time two years ago. At first it was a PF9 and now a Sigma 9. I felt that a 9mm are adequate for SD but as I read, only in some cases. Ok then, so I looked up the 40sw. Lots of mixed reviews but most says it is indeed a pretty powerful caliber.
I decided I want one and got my Sig P250c in 40sw last April (Fools Day duh). I had two boxes of ammo in advance, WWB 165 FMJs and Win PDX1 165 BHPs before I picked up the gun at the range. I took my cleaning kit along to prep the gun before shooting because the day I bought the gun I get to shoot for free.
Now I know what they mean about the recoil. It does kick hard, especially the PDX1s. I still hit the target (at 25 feet) in the green so that wasn't bad. After a few trips to the range, my groups got smaller and more tolerant to the recoil. I love it.
Funny thing is, my 9mm feels inadequate compared to the 40 but I still shoot it because it shoots tighter groups than the 40. Also it's cheaper to shoot.