I had a screenshot comparison like mosu84's ready for my post of last night but I didn't want to go to the hassle of pasting it in. It was for AA vs. Delta, though with different cities and times. The results were pretty much the same-not as dramatic as mosu84's but markedly in AA's favor.
Anyone can try this him or herself. And remember, this just shows who says they have low level flights on which days. It does not take into account directly either the additional miles needed on DL for low level, or whether the days shown with low level availability on DL's calendar really have flights at that low level on those days.