It´s not just the rendering times with radiosity the is a problem with animation, there is also a shadow flicker. You get the same flickering thing with some of the FG gethering solution like MR, but then you have often the choice to bake light maps into the texture maps.
I have used and seen what MR and Brazil can do and both renders are very fast with FG(GI). Hope that Yves will look into this later on for A:M. Looks like he´s doing a very good job on the A:M render now.