I use a 50mm f/1.4, professionally—all the time—I certainly wouldn't mind having the L version, but since I'm usually covering events, concerts and weddings, it's rare that I will end up using a high speed lens at this focal length wide open—and the 50 1.2 is a lens that begs to be shot wide open. Typically I'll keep my 50 around f/2-f/2.8. I've found that I like it a lot at f/2-2.8. It just renders a very nice look.
One photo attached here, at f/2.8 from a wedding I shot a few weeks ago, nothing particularly spectacular for showing off the lens, but it's a shot I had handy. 7D, ISO 1600, f/2.8, 1/250th, bounced flash.
The 24-70mm f/2.8 II is nice, of course, but I find that range so uninspiring that every time I've used a lens in that range (I used to use the older 28-80mm f/2.8-4 L) I'm disappointed with the shots...seems like they always end up rather "flat" to me. There's no substitute for zooming with your feet when it's possible to do so. There's also something to be said for the way small lenses can allow you to get closer to the action without freaking out the subject and allow you to get more dynamic compositions.
Plus the 50mm f/1.4 is super light, much lighter than a 24-70mm f/2.8, and weight definitely matters when shooting weddings & events--you're on your feet for 10+ hours shooting, and since I shoot so much with my 80-200mm f/2.8 L when I'm out, it's nice to be able to take a break from it with something like the 50/1.4 and give my arm a rest--plus it's just a fun lens to shoot with, and if something where to happen to it, it's easily replaced.
Maybe one day I'll grab the 50/1.2, just because I do like superfast lenses, but I don't think I'd get rid of my 50--it's a nice lens to leave on all the time because of it's size and speed. Actually, scratch the 50/1.2, I just need to save up $3-4K for a used 50mm f/1.0 L.