Gary... hey man... what did you wind up with the Mossberg or the Winchester?
Time passes; experience happens; views evolve.
I really love the Mossbergs and have come to love my 870P as well, but in the end, if I had to settle on just one shotgun for defense, I've come around to the Winchester 1300 Defender.
Reasons?
Capacity: with just an 18" barrel, the Winchester 1300 Defender is an 8-shot gun with NO extensions (nor extension brackets) to fool around with. These have a full-length, one-piece mag tube which I LOVE! (Extensions are not my preferred way to gain capacity, therefore my 870P remains a 5-shot, which I'm fine with, during the day.)
Speed: The 1300 action is really slick and quick.
Of course, reliability and durability are a given among all of these models being discussed, or they wouldn't even be in the running.
I still like the controls on the Mossberg the most, but have come to realize that you can get accustomed to the controls on any of these models.
SO, while I sure don't want to give up my 500 and my 590
Nor my 870P
When day turns to night, my primary, go-to shotguns for home defense are these, each (since this photo was made) now equipped with 6P clones housing Malkoff P7 and M60F lamp assemblies, and Surefire Z59 tailtaps.
Amidst all the hoopla surrounding Mossbergs and Remingtons (both great guns!) the Winchester 1300 Defender is an "under the radar" favorite of many who are in-the-know about them.
Here are all three of my 1300 Defenders: