DrRacket is not as easy to customize as Emacs is and it, by default, offers a different mode of exploratory programming than the one SLIME users expect. In DrRacket you don't evaluate a single form, you just execute a module and then are dropped into it's namespace. If you change a definition in your module you need to re-read all of it or alternatively copy-paste it into the REPL, which is not convenient. I found that the SLIME/Geiser/Emacs model is better for really tiny stuff, while DrRacket's is better for longer scripts, where there are many dependencies.

Anyway, while both ways are ok, they are not exactly equivalent - is what I wanted to say.