Shot my buck this year under one of them umbrellas. Love them and use it all of the time. Have had many deer pass by while under one and there doesn't seem to be more than normal that pick me out.
Wind can be a issue with them though. Hate hunting in the rain or when the skies can open up at any time but I would rather my clothes be dry then getting pelted with rain in Gore Tex.
One thing though, with hunting in the rain comes a responsibilty to be very sure of your shots.
My rifle is a black rifle