The 50mm 1.8 gets too much CA for my taste... I did a portrait shoot and bought one of these to get me by. I was NOT HAPPY AT ALL and returned it a few days later. I have shot an 85 1.8 and I liked it but have been so blessed with L lenses that it makes it hard to purchase this when I think I would rather just wait and get the 1.2 later. The feedback you are giving is amazing and I really appreciate your time...
What is your experience with the original 24-70... Is it not worth my time... Would i be happier with my current set up?
Using Lightroom 4 CA is a complete non issue, it takes 2 seconds to completely remove it
i wouldnt let that be a concern my main issue with the 50 1.8 is the 5 blade aperture and not so great bokeh
vs the 1.4 etc that is
I personally have the sigma 85mm (I chose this over the L even after testing side by side) which is my absolute favourite lens Its amazing however if you are budget constrained i would still say the canon 85 1.8 is going to flat out give you the best images for your money.
maybe see if you can go test a few out in the shop but if CA is a concern download the trial of lightroom 4 and see for yourself its really a non issue

I have always been disappointed with the 24-70 mk1 i have used they have never been as good wide as my 16-35 is and never as good long as the 70-200 f2.8 or the 50mm f1.4 for that matter