I used to carry a P64 in 9x18. I have also carried various .380s. After doing a lot of reading and research I have concluded that, IMHO, these calibers are insufficient. I have a CZ RAMI in 9mm that is going through the customization/trigger job process that will be my pocket gun from time to time. For now, my do it all carry all the time gun is my CZ 75 Compact 9mm with Cajun Gun Works race hammer, short reset trigger and Meprolights. Why not carry your best gun all the time?
I carry a colt junior 25 auto but only for backup. It fits nicely in my pocket it is a very old one a 1959 made one but it shoots great.it is a good back up for my smith &wesson 360 pd.