Ok, GavinMcG, just try to write web application in racket, based on official documentation. I assure you that nothing will be clear to you, huge questions will just fly over your head, and if you then ask for help on the Racket group, the people there will make fun of you. Been there, done that! Believe me.
Yes, and now, after three year and countless hour spent the new version (RacketCS) is running slower than the old one! Congratulations to Racket development team - well done! :)
There are some very valid reasons [1] why we should stay away from Racket: toxic community, toxic people... And come on: no one has ever really used Racket to write some decent nontrivial web application, documentation is awful (and, please, don't count HN here, cause HN is written in Arc).