once you go 5D, you'll look to replace the UWA
+1 - highly likely.
At lower isos, much better color rendition, contrast, raw files, better bokeh, even from the nifty fifty, ect.
My boy's 3rd bday is coming up, and I was just looking through photos from the delivery room - he was born a few subway stops away from B&H, so I decided to swing down and pick up a nifty 50. It was a good decision -
Napping with mom by heightsfidelity, on Flickr
IMAGE LINK: https://flic.kr/p/9PaBVU
Chillin' by heightsfidelity, on Flickr
Now I just have to figure out where those three years went...