First of all, I'm not a serious shotgunner. Well, not yet anyway.
I've got a moss 500 20", 7 round for the house and it feels good to me, but I just went out the other night for my very first round of trap ever. I shot 2 of my buddy's 870s. The 870s were tighter and smoother in the forarm and felt like a more precisely built action.

As far as 3.5" shells go, I've heard you would really only need them for geese. Just repeating what I've heard. Good luck.

Keep 'em all in the Bull.