I carried one or another issued 6906 for several years. Fired upwards of an estimated 45+K rounds through one of them (yes, it required some maintenance and parts replacements

). Good pistol. I rather liked the ones I carried.
I found that the thick grip of the 6906 was improved by the Hogue wrap-around grips w/finger grooves. Weird, since I didn't like them on the 59XX guns, and the Hogues for them didn't have the added finger grooves ... but there you go.
Using a couple of very good quality kydex and leather holsters for the 6906, I still found it to offer more of a lump against my side throughout the long hours of days & nights than my 3913 (which also wore Hogue panels most of the time).
If I'd been given my druthers, I'd have cheerfully traded my issued 6906 for an issued 3913. The extra 4 rounds of mag capacity just didn't concern me overly much. (I finished my career carrying an issued 4013TSW, followed by a 4513TSW ... so capacity varied now and again.

)
While I've always had it in the back of my mind to pick up a nice used late production 6906 someday, I still feel my 3913 & CS9 are slimmer enough through the grip frame to be a bit more comfortable. They also pocket holster a bit better.