N.S.
I actually have the Britax Marathon. When I looked at them, I also looked at the Diplomat and liked both, the Marathon and the Diplomat. I decided to go w/the Marathon b/c it had a higher weight limit. It does look huge in my van (I have an older Toyo Sienna) but my son loves it! And so do I. We are used to the size now and I'm glad I got it. I don't know if you are thinking of buying them at a local store. Before you do, check out www.albeebaby.com. We got our Marathon for $80 less than what we would have paid at BabiesRUs. And Albeebaby has free shipping over $100 or $150.