I think it's quite good. I don't know how practical the "Save with download manager" feature would be to implement. Also, that's how a lot of warez sites get their illegal files across..like with "Save target as" - personally I wouldn't want to see more promotion of warez, and I think this would make the whole illegal file sharing thing much easier on people.
I think it would be nice and useful for many people however, if they could, for example, right click a URL link and then have a menu that expands so that there are a list of browsers to choose from.
My 2 cents.