17-55 has more CA on the sides compared to 24-70.
Where did you get this generalized statement from?
17-55
http://www.photozone.de/canon-eos/178-canon-ef-s-17-55mm-f28-usm-is-test-report--review
24-70
http://www.photozone.de/canon-eos/184-canon-ef-24-70mm-f28-usm-l-test-report--review