Another gun to look at (if you didn't already buy) is the stoeger 2000. I've had one for two seasons now and it has performed almost flawlessly. As long as I keep it semi-clean it shoots well (semi-cleaning meaning don't let 4 hunts worth of mud build up inside the gun). I've probably shot 3 cases of shells and it cycles perfectly.

Most have been ducking in the mud, cow $hit, etc. I bought it for just over $500, and that included camo coating, chokes, etc. Much higher quality product that the new 870 express guns.