duk, you have just entered another category into the mix. The "specialized" shotgun. I started raising bird dogs in the early 70s and have killed a lot of quail. I've used 870s, and 1100s, Brownings, and even a Browning Satori. I will take an 870 Wingmaster with a 24" or 26" barrel and kill as many quail as anyone with a Model 12 "built to quail hunt". It may balance better, cycle faster, and point quicker FOR YOU. But that doesn't mean it will for everyone else. What you just said is YOUR OPINION, not the law. If it suits YOU, then by all means never hunt quail with anything other than a Model 12, but the Model 12 is YOUR preference, and it doesn't not mean it is a better shotgun. I have an 870 Wingmaster that is probably as old as you, and is has nice wood, nice bluing, and the fit is excellent, but I don't claim it as the NICER gun. It is what it is to me, just as your are what they are to YOU, but not necessarily to anyone else. I will hunt quail, and then change chokes, not shotguns, and step into the duck blind and do equally as well.
It is like a Corvette. In my opinion a Corvette would make a damn nice tradin on a good 4X4. Some would opt for the Corvette.
An 870 with a 3" chamber and 28" barrel (usually with a modified choke) is not the ONLY 870 out there, and is a poor example of a comparison to a quail gun, but even there, I have seen it done, and done well.