Blue screen backdrop question

I hope this is the right place for this question. Recently I came across a very nice picture of my wife except for the yuk in the background. In post editing I replaced a background which favors her color type. I got to wondering, why not use a blue or green screen for portraits and then apply a favorable background in post editing using a chroma key editor or some such? Is this ever done? What are the pro's & con's?

Depending on the situtation you can be looking a very tedious PP. Getting the background lit evenly and then having the subject far enough away that you get no spill onto them from the background color are the major things to worry about. This is what I have found in my experience. I have been playing around with white lately and prefer it. Theres a good read here: http://www.zarias.com/​?cat=13

budbon wrote in post #5833807
I got to wondering, why not use a blue or green screen for portraits and then apply a favorable background in post editing using a chroma key editor or some such? Is this ever done?

Many photographers use that technique.

I'm working on a project now using it. Here's a link to my blog entry:
Wrestling Team Poster: Part 1 - Chroma Key Cutouts