Hello, I have a dilema which I know is typical. I have a 50D and the 17-55 S f/2.8 and the 100-400L. I shoot a lot of birds and the like with the big lens, and oceanscapes with the 17-55. I want to go wider. I'm looking at the tamaron 11-16 f/2.8. But for the same price or less I could get a used 5D. I would then keep the 50D for birds, sell the 17-55 and get a wide for the 5D. So my question is, how much better IQ will I get out of the 5D compared to the 50D? I'm also starting to get an itch for some milkyway. I've used the 50D at 3200 and the noise is pretty bad. Is the 5D significantly better at that high of ISO?