fg12351 that sounds like my story- my first handgun was the G23 and I just bought my 3rd gun the Sig P239 in 40 S&W for the same reasons - it's slimmer than my P229 or G23, it only has a 3.5" barrel and it is light enough to haul around all day. Round capacity is as stated 7 rounds for the 40 and 8 for the 9mm.
Is that a detrement for the weapon - NO because that little gun feels so good and shoots so accurate you won''t need any more rounds (although I normally carry an extra mag in my pocket).
You could load the mag - put one in the pipe and drop the mag and add an extra round if you wanted to but I don't like doing that myself.
That P239 is one sweet little pistol. It took me a few times at the range to get used to the DA/SA trigger but now it's no problemo. I had considered getting the Kahr PM9 but because of availibility of the Kahr went with the P239 with no regrets.