I remember prior to these guns earning the moniker of the "Wonder Nines" (due to S&W investing in state of the art Computer Aided Manufacuring), they had a reputation for needing to go to a gunsmith for "tuning."
After Smith improved their manufacturing quality, they had a reputation for feeding anything you put through them. Prior to that, you kind of needed to know a reputable gunsmith.
I'd carry my 6906 with no hesitation. It conceals well too.