Amadeus,
When it comes to firearms, I'm a civilian w/civilian needs.
Please define "civilian needs".
I now have two 870's that are/will be used only for Trap and occasionally Skeet. Their magazine plugs stay in and they're put away. One of these is an older 870TB (the subject of another thread) which I have yet to shoot. The other is a standard 870 field gun which I've modified with a custom stock specifically for Trap.
When you start using an 870 for Skeet, you will learn how fast and accurate you can be. Skeet doubles are work with an 870 but it can be done; I've done it and I'm not what I consider to be an expert with an 870. Trap is a good game for an 870, very doable.
But let's say you're home one night and four guys come busting through your door; you happen to have your 870 ready with 3 rounds (which at room distance hit as a solid mass with the wad). You empty the shotgun quickly and effectively because you've practiced, and you now have three bad guys down; the fight is down to just one bad guy across the room and you with an empty gun. His cheap pistol is coming up, what are you going to do ... do you feel lucky?
"Civilian Needs" in this day and age of home invasions has changed a lot from the past. In addition to the two game guns, I have another 870 configured for HD -- 5+1 rounds of #4 Buck. There's a large caliber pistol backing it up.
Do I expect to be invaded by a half dozen bad guys? Nope, not likely, but why limit my ability to defend myself if the need arises. At least remove the magazine plug and give yourself 4+1. Those extra two rounds could save your ???. There's no need to limit mag capacity. You single load for Trap so the 870's mag capacity is never an issue.