I will not argue that detachable magazine weapons are much quicker to reload, but a shotgun is a very different defensive weapon than a pistol, carbine, or a subgun. It's effective range against human targets is much shorter than most people think. When deployed within effective range in a home defense situation, there will not be any need for anymore than 8 shots. Probably the most effective accessory, after the install of a weapon light, would be the cheap but effective elastic buttstock shell holder.
I respect your difference of opinion, and welcome your comments on the subject. I've just seen way too many pinched receivers (from side saddles), magazine tube problems (from crappy mag extensions), and operators who think because their shotguns print five of the nine pellets of 00 buckshot on a patterning board at 20 yards, that their weapons are going to keep them alive. I would rather see a shooter (civilian or cop-doesn't matter) with a base combat shotgun burning $$$ on shotgun shells and range fees, than I would a guy spending $800 or more to complicate a fundamentally sound weapon.
Please take my comments with a grain of salt, because I am not an big advocate of the shotgun for law enforcement or civilian defense. I have far more data,background and training on the use of pistols and magazine fed carbines for defensive work. Personally, I use a shotgun to shoot things that fly, and either a Colt M4 or a Sig Sauer P229 for things that are trying to kill me. Be safe out there!