Since I have to carry either a 6906 or SW99 .40 every day as my issued weapons, and will soon be trading both of those back in for an issued 4566TSW, I generally carry something lighter on my own time. Not always or exclusively, mind you ... but generally. There are certainly some instances and situations where the issued duty weapon serves as the off-duty weapon, as well, or I simply feel like carrying one of my larger framed and/or heavier personally owned weapons.
Anyway ... MOST of the time ...
That 'something lighter' is generally a 642-1, and to a lesser amount it sometimes includes one of the following ... G26, G27 or CS9. Just depends on my manner of dress, planned activities, and where I may be traveling. An evening down at the local cigar lounge may only 'require' the 642-1 or the CS9 being dropped into a light jacket pocket. If I'm wearing a jacket which I don't plan to remove while out and about, then one of the little Glocks often fills a belt holster. The G26 gets the nod more often than the G27.