Well, I carried a 669 for a couple years starting in 1989, when my department made semi-autos optional. I switched to a 6906 when one became available. Back then, I carried the same gun on and off duty for a while because of the newness of being able to carry a semi.
Both carried the same but a sturdy holster was necessary, because 12 rounds is a lot of weight out there in free space above the holster. That said, they were comfortable IWB or OWB. OWB, other than that different balance in the grip, was no different than carrying a revolver (I carried everything high-ride.) IWB simply meant having the grip frame sitting on top of my belt. It did stick out more than a revolver, though, so I had to be more careful how I dressed.
I've since stopped carrying the 6906 daily because my other options are lighter, and I'm retired.