different idea but along the same lines as you, vancem:
Forget the "points".
Add up the percentages. If the combined usage on the floor = 1 (or 100%), then you suffer no team possession penalty while playing half court. You suffer a moderate penalty for up-tempo.
If they add up to .9 (90%), then you suffer no possession penalty while playing slow-down. You suffer a moderate penalty for halfcourt and an extreme penalty for up-tempo.
If they add up to 1.1 (110%), then you suffer no possession penalty while playing up-tempo.
Simple addition. It'd make some players more (and some less) usable in my eyes and would change the self-imposed restrictions many owners put on themselves as to who to use, where and why - without making things "too easy" or simple.
I almost always have 110%+ usage out there anyway, so it wouldn't really effect me, but I'd be able to maybe feel more confident entering a league with a different type of lineup.