Do a search
There are threads talking about the problem you mention (flickering, etc.), but it's not clear whether it affects all 24" ACDs or just a few. FWIW, I have a 24" ACD that I recently picked up from the refurb store, and it works just fine with my 2011 MBA. (It's a great display and has the right resolution for me.) Maybe all the recent Thunderbolt updates solved the problem, but I do not know.
Good luck.