I make no bones about it, I think Gardner adds a LOT to the show, by virtue of his freakishly encyclopedic knowledge of History, the Constitution, and legal precedents. In that way, he's almost exactly the opposite of Ian and Mark.
On top of it all, he's a principled
anarchocapitalist "Free-Marketeer", like Ian, but not so in-your-face.... rather, he comes off almost as a "moderate", like Mark. He makes anarchocapitalism digestible to the general population.
Last but not least, the whole dynamic of the show was more enjoyable with Gardner on. Maybe just because Gardner stopped Ian and Mark bitching at each other like an old married couple

Yay Gardner!
Anyways, that's my take. What say y'all?