4 buck'll handle most jobs, but I don't know why Remington would start championing it, if in fact that's what they're doing.
1 buck has long had a rep as the quietly best choice because the larger number of pellets ultimately adds up to greater "acreage" of wounding compared to the more traditional and thoroughly dependable 00 buck, while still achieving minimum penetration per FBI protocols (which #4 does not).
Thing is, I don't think there's a 1 or 4 buck Remington makes that'll pattern nearly as nicely as Remington Managed Recoil 00 Buck. I've run the pattern tests at 22 yards with an 870 18" open cylinder and in that particular gun Remington's #4 and standard 00 buck did the predictable one inch spread per yard traveled. Don't know if you've recently looked at an approximately two foot spread on a human silhouette but it looks like a few good hits and several troublesome misses. Both these loads kicked significantly more than Managed Recoil, as you might expect. I'd wager a Remington 1 buck would perform similarly.
Not sure what Remington's doing with their Managed Recoil 00 buck, but at the same 22 yards it cut that spread by roughly half. I'll take it.
Now the 1 buck load I'd stake things on is Federal's LE Flight Control; that stuff in 00 buck is incredible at distance -- hand-sized patterns at 22 yards -- and I've no doubt their 1 buck offering is excellent, too. Good luck finding it anywhere, though.
In the meantime, to heck with standard loads, 00, 1 or 4, and their kick and spread. Remington's Managed Recoil or Federal's Flight Control here, please.
As for Remington's Home Defense line, I think it's discontinued. Don't know why, but presumably it wasn't a seller. I'm largely in the "birdshot is for birds" camp, but people in apartments, town homes and condominiums do have special circumstances and I wouldn't begrudge them trading best terminal ballistics for increased care for innocents very near them, so long as they were making an informed decision.