I was in the same situation about 6 months ago. I was going to sell my 24-70L to pick up the 50L. After posting a similar thread, I decided to add the 50L to the 24-70L.
6 months later, I'll tell you that I use my primes about 90% of the time over my zooms. There is a time and place for zooms, and when I need versatility over speed I'm glad I have very capable zooms.
If it's possible (financially) for you I would suggest adding the 50L to your current setup. The 50L is definitely something special. I've produced images with the 50L that the 24-70L just can't.
The 50L isn't the sharpest lens out there, but the images produced by it are amazing (for lack of a better word, it's something words can't describe).
-tyler