RE: Mossberg 500 vs. Remington 870
I have an 835 for turkeys and an 870 for everything else. A good all-'round gun, I would take the 870. I would look at an 835 if you want a Mossberg with some use for turkeys. My 835 is devastating. My 870 is a nice light gun good for wing shooting. The 835 ulti-mag is a little heavier but don't regret it for turkeys.
I am not going to prefer one over the other because I don't know your whole situation, but I think you can make the right choice off of the feedback.