Continuing the series.
One nice side benefit of treating low stats as specific disadvantages is that for the mental stats, you avoid the tired old controversy of "oh, I must now play my INT 4 character as a moron." Really low Intelligence here gets you a reroll and a visual disability. (Hint: Blind characters make good clerics. Get a guide dog or trusted henchman. Seek out medusas.)
Kind of low Intelligence gets you a minor cognitive disability. Either way, you can be as clever and puzzle-y as you want to be.
Come to think of it ... there may be something to really high scores not giving you super big bonuses, but just a +1 and a special advantage like photographic memory, magic resistance, etc. I have been thinking about stacking and high levels, and I'm not sure that allowing 10th level characters to get +15 to hit from levels, magic, and stats is really where my rules should go.