How google friendly are responsive themes

I have a website that is doing well in google, its my business website and 98% of the work I get comes from my website. Someone has pointed out recently that my current theme has errors in it and that I should install a theme that is released under GPL. I’ve heard people have dropped rankings when changing themes and that some themes are more google friendly than others (i.e Thesis) . What I want to know is how google friendly are responsive themes?. If I was to install a responsive theme am I going to take a hit?