...I'm mostly posting this for posterity. It's taken me a lot of time, but I have stumbled upon a smooth lander build that really just takes the game and pushes it into an exact middle point between melee and brawl (instead of the 3/4 towards brawl position it is regularly). A bit faster, a bit more offensive play. Think of it similar to the Smooth Lander Heavy Gravity builds, but without the need for heavy gravity, and thus free of the issues associated with using it.
Really, SL on its own would be pretty bad, since it would only make the strong stronger for the most part, but if you add additional mobility in there, so that every character can tap into combos, that's something else. On a personal level, I think it works quite well, and I think it proves that SL can be a really good thing:
Anti-Leap Brawn Badge + Sprinter Protection Badge + Smooth Lander Agility Badge
-27 Atk
+15 Def
+50 Speed
at 1.1x Knockback.
Basically, the process involves upping overall mobility, fast falling speed, and landing lag decrease via the speed stat/smooth lander/sprinter, and then compensating the loss in knockback from the attack stat value by upping the knockback scaling in the options menu (I fine tuned the attack stat until knockback values were nigh-identical with vanilla Smash 4). This results in a game where combos are much more viable, but knockback growth accelerates ever so slightly higher, resulting in a much faster game overall.
I personally prefer standardized equipment for all characters, as I do believe that individual equipment in tourneys would be a total nightmare, so that's what I've done here. Don't get me wrong, though. This build, well, it's basically impossible to get, it doesn't consist of any challenge reward equipment pieces; I'm posting this just to show what equipment can do. I'm posting this in the hopes that maybe someone else out there has the same equipment, and could try this out and share their thoughts.
I'm going to try and upload clips to my Youtube Channel, as proof of concept. Again, I have no idea what else to do with this, since I can't exactly share it, but maybe someday, if we can hack equipment, we could do something with it. I like to think of it as 'Smash 4 Enhanced' more than anything, since it feels identical to the original game in terms of knockback/setups, but with marginally faster knockback growth and way better combo-ablility. I play this weekly with my friends, who all play for Glory, and none of them feel alienated by the differences.