Hey 2HOW, Rob Pincus at the Valhalla Elk Mountain training facility in Co, and his ICE training, ran through this scenario with shotguns for home defense.
http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoID=1322226816Since your post didn't mention what type of application you want, target, clays, hunting, SD, etc,.. if I'm missing the mark, I apologize and just disregard.
For a home defense environment, Pincus demonstrated with walls, halls, bedrooms, and simulated badguys, the effects of different 2 3/4" and 3" rounds in the home with standard construction, 2X4 studs, and sheetrock walls.
Surprisingly to me, #9 , 2 3/4" shot created the most damage at close range, (less than 7 yards), without overpenetration into an adjoining bedroom where one could have the rest of the family in a safe room type scenario.
Slugs WILL work, no question. Depends on your residential environment, neighbors, kids, the mother-in-law, (nevermind)

#2, 00 Buckshot, 9 pellet was the next choice. But all work. His point was TACTICS. Stalking the BG with a 1300, as you know, requires a really good sense of who,what and where.
Your talking about one of the most powerful defensive platforms at close range on the planet.
Hardened shot and buffers won't make a difference in the home defense scenario. The lethality will be well, its a shotgun at close range,...
If you were referring to another type of application, other than home defense, I apologize.
My Rem 870 is kept "close" with #2, 00 Buck, staggered with #9, and the last 2 are 3" Sabot Slugs, if it has to get to that point, increase the damage potential, until I get my "black rifle". I hope it never gets to that point at all, but I am a firm advocate of the castle doctrine.
Again, sorry if I misunderstood your post.
Just my .02 cents.