I've been carrying my 6906 since I got it a little over a month ago. A couple of weeks ago I bought my M&P40 with the intention of carrying it IWB as soon as I got a holster, which came in a couple of days ago. I've been carrying it (and wearing it around the house more just to get the feeling of it) and I'm stuck...I don't know if I prefer the M&P or the 6906!
The only thing saving me right now is that I've got an awesome holster for the M&P (Comp-Tac MTAC) and the one I have for the 6906 is "ok". I want to get a good IWB for my 6906 so I can really compare. I wish I could get an MTAC body for it but they don't make it. I'd like to get a Simply Rugged "Cuda" with the IWB straps, but before I lay out the money I think I'll get a Kholster and try that (I've had good luck with the Kholster before, and as long as I can get something close a little application of a heat gun will have it fitting in no time).