This would be a great feature to have. However, all I really need is detection and renaming/moving support. I don't really download movies, I buy Blu-Rays, or DVD's if the movie I want isn't available on Blu-Ray.
I'm am currently moving away from Media Center Master, after a few years of using it I am tired of the slow interface.
I was told about Sonarr from one of the Emby developers a few day ago, and love it. I prefer the web-based gui over a traditional one.