What Brooks shoe is most similar to the Glycerin? Is it the Radius, the Axiom, something else, or is there no comparison? I like Brooks and I really like the Glycerin, but at $110 a pop, I'm wondering if the Axiom or Radius would be almost as good for $20-$30 less. I also like to switch models from time to time just so I'm not always running in the same shoe. I am hoping to stay within the Brooks brand just because I like the fit and feel of their shoes.