With the 1911, you're holding a piece of history, albiet one that's evolved over the 100 years its been around. It feels great--like a double walled brick house in a windstorm, but in your hand. Its just a very special sidearm--it just screams 'real deal'. They once were not known for accuracy--they were orginally pretty much for close quarters warfare only and if you missed or ran out of ammo, the weight of a 1911 thrown at the head of an enemy was probably gonna kill him just as well. With time and better (closer) build tolerances, they've become very accurate and their considerable weight manages recoil nicely. But, as with most quality guns built to close tolerances, a piece of sand or grit can hang you up. It's not as easy, especially as an M&P for a novice, to break down a 1911. They're both great guns, and it'd be great to have both, but if I only could have one, I'd give the nod to the M&P. Get yourself a Gerber LMF knife to go with it. If you get the 1911, get a Kabar.
You also save a considerable amount of money. In fact with what you save, you could buy an M&P 45, then with the money left over, almost buy a 40, and then interchange 40 and 9mm barrels, giving you three excellent guns for the price of a mid range 1911. All of the above guns are very reliable and accurate although as indicated, the 1911 needs to treated a bit more carefully.