You compare a fixed focal length lens with a zoom. It is natural to have less distortion. If the zoom IQ even matches the fixed lens at comparable apertures it is enough of an accomplishment for me.I much prefer the 35L myself. The 24L II did not impress me much. Great lens, but too wide to be very useful for versatile shooting. I think the IQ of the 35L is better as well.
Plus, I have the 24-70 II which has better IQ than the 24L II anyway at comparable apertures. Better corner and edge performance for one.
The 24 L has MUCH less distortion where the 2470 II is frankly a dissapointment. That is on of the reasons I bought it, but serious AF issues and, as you say, I found my favorite lens in the 35 L as it is epic in (almost) every way, and why I am waiting so bad for the mkII to show up...
Well yeah, but as quoted above it was indeed compared
To the 2470 in the edges and corners. And for some users distortion is a big deal. So saying, just get the 2470, it is as sharp, is not the whole story. I use the 2470 very carefully at 24 and I really dislike the distortion, sharpness isn't everything.