Like I said, it is confusing... twisting the terminology... I don't know anyone who does that...
I agree, which is why I'm annoyed by incorrect terminology like clip when we mean magazine, bullets when we mean ammunition, or point blank when we mean contact close. In the end no one knows what anyone else is talking about, and it takes additional explanation to make your point.
With respect to box magazines on slide action shotguns, I think the disadvantages out-weigh the advantages. Clearly the advantage of the box magazine is that you can have more rounds available to you with a long box magazine, and that with spare magazines, reloading is much faster than stuffing rounds back into a tube magazine. To me the lines of the gun are spoiled with the box hanging below the receiver, and I would think that gun handling would become unintuitive. However I am not opposed to long magazines on rifles, so perhaps the validity of this complaint is questionable.
A big advantage a shotgun has over a rifle is the wide array of ammunition that is available for it. A serious disadvantage to a shotgun having a box magazine, is the inability to quickly select a different type of ammunition from what is loaded in the magazine. For example, lets assume you wanted to fire a less lethal round when the magazine is loaded with slugs. With a tube magazine, you retract the slide just enough to eject the chambered round, without releasing the subsequent round from the magazine. Drop the selected round in through the ejection port, and close the action. This could be repeated as often as necessary, yet a lethal round would remain instantly available by simply running the action and firing.
In the same situation with a box magazine, switching rounds means either switching magazines, which denies you immediate access to the lethal rounds, or partially dropping the box just enough to drop the select round through the ejection port, close the action, then reseat the magazine, and fire. If it sounds clumsy, it probably is. There is a conversion for Mossberg shotguns that attaches the box magazine to a replacement magazine tube, thus retaining the elevator loading feature within the receiver. Quick changes of ammunition should be possible with this system while having immediate access to the rounds in the magazine, but I can't help but think that attaching a 6-10 round box magazine to the gun ahead of the balance point will make handling awkward. Would the balance be affected more than by rounds in tube magazine? I don't know, perhaps not, but it looks like its possible. Be this as it may, if you intend to use a box magazine on a repeating shotgun, I believe the system for the Mossberg would be superior to one where a magazine follower replaces the elevator in the receiver.