That 870 is "better" than mine only inasmuch as you've found the right front sling swivel. Otherwise, I vastly prefer mine, because it has the Knoxx recoil absorbing stock. I think that bandolier could pose a serious problem if it got wedged in the way somehow. The tube holds more than plenty to settle any indoor situation.
I load mine with 5 rounds of Winchester 3" Mag. 00 buck in the 4 dram equivalent. I could not use this load, if not for the Knoxx stock, and what a monster! 15 .36" balls @ almost 1,400 fps. If a man forces me to use this against him, we are finished talking!
I believe that a sling is a very good idea, because it moves the gun to be accessible, but your hands remain free. I saw one that was set up with a streamlight, built into the forend, and that might be a good idea. The big thing is to have a really big gun, and keep it as simple as you can.
It is also a supremely good idea to have a cell phone readily accessible, and call 911 before any confrontation begins. This will get the cops rolling, and the recording may well save your bacon in court.