I have had a 870 for about 13 years now with no broken pin. Great gun for the price. I now shoot a Beretta over/under for skeet, trap, 5 stand and sporting clays. Another great gun but very expensive.
I would much rather have the 1100 for hunting because it is an auto and will not have as much recoil. My 870 kicks like a mule and my buddies 1100 is so much nicer to shoot.
The 1100 will be around $200-$250 more. You can get the 870 for $250 most anywhere and the Mossburg 500 for $200 most anywhere.
The nice thing about both the 870 and 500 is that they sell quite a few accessories for both of them to use in home deffense and hunting. I would prefer a pump if I was going to use it for home deffense.
Yes, get a 12ga.