Well Leonard there are pros and cons to both types of holsters, but there are two factors that should be considered when making a selection for OWB or IWB and one is comfort and the other is how you dress around the weapon, IWB is good for most any wardrobe style while OWB may necessitate a change of clothing, not to mention your body build.
I use a Minotaur MTAC for all my M&P's on a daily carry basis and a Blackhawk Serpa for the range as an open carry option. In Tennessee we have a carry permit you can carry concealed or openly it is your personal choice here, but I usually carry concealed.
The Minotaur MTAC is very comfortable to me at about 3:30 or 4:00 with great retention. I carry a fullsize M&P40 daily and am not a large man...I am 5'6" and 140 - 147 pounds and no one ever notices printing (even myself) but I am used to carrying so it is just second nature, to someone new to concealed carry it will not be it will be like the pimples you had in high school and you are certain everyone else notices the same one you are concerned with and pick at daily in front of the mirror ( glad those days are long passed )!
Get a quality holster that you can try at the store in person (with an unloaded firearm) and give it a test run kinda like buying a new pair of shoes you know that there will be a breaking in period till the new holster will adjust to you, but if it don't feel right at the store try something else.
Do not cheap out and end up with a drawer full of useless holsters that you never use (Note to self throw out all those crappy holsters or give them away TODAY)!
