[Chaos]

That sort of defeats the purpose of diminishing returns on stats, doesn't it?

Not really. It's how slamming a stat to 80 through points is currently a complete waste, since once you hit that point, you have to hit the limit on Stat Boosts before you even see any real 'return' from the scaling, and even that's incredibly minimal. It also makes certain effects, such as the Dragon King set, completely useless. (When the stat bonus you'll get is either matched or outclassed by more easily obtained equipments, until a point where your returns are completely shot, you're not really going to bother)

What I'm trying to suggest is a way to let people who pump a stat to hardcap to see a little more from boosts, instead of having to go all in on stat boosts just to see a +2 to the scaled total. Unless, of course, your intention is to make people have to build their base stats around their boosts, alongside everything else.