Im posting this in the cameras section, but it applies equally to both lenses and cameras.
Here's the backstory: I sold my 24-70 and 135 and have my 1D Mark IIN up for sale. With the funds from these sales, I was going to buy a 1D Mark III, and either a) upgrade my 17-40 to a 16-35 and still have a little left over or b) save considerably more and buy a 24L II.
I LOVE MY 50L, no doubt about it. I love it on the 1D and the 5D alike. The 24L has been super appealing to me lately since I've been really wanting to use a wide angle with beautiful blurring for close up portraits during travel and weddings.
So will I see huge upgrades if a trade up for a 1D Mark III over my IIN? I shoot a lot of available light while traveling so some better ISO performance would be nice. I don't need the extra fps or resolution but MFA might be nice.
Will I be happier with a 24L II to add to my line-up to be used on the IIN and the 5D?