While I'm waiting for my lifetime permit to return I'm shopping for an M&P 45 (4 1/2 inch barrel) holster. I've Never had a permit or carried so I have no reference point to guide my purchase. What are the advantages and disadvantages of IWB and OWB? Does anyone have a manufacturer recommendation for an IWB and OWB holster. The only thing I'm set on is that the trigger must be protected in the holster and I'm a southpaw.