Justin's reasons for selling his 24 match up well with why I never got one.
Most of the time that I'm looking for 24mm, I'm almost instinctively reaching for the TS-E 24. And I'm not looking for speed at those times.
I think most people would be very happy with either the 24 f/1.4 or the TS-E 24, but I don't think very many would get a lot of use out of both. They're both 24mm L lenses, yes, but they're not at all interchangeable and have no overlap except focal length. One might think that therefore there'd be room in the kit for both...but, as I see it, if you're happy with the one the other isn't going to interest you much except as a very expensive novelty.
And I couldn't be more thrilled with the TS-E 24....