I'm a geneticist whose (work) code is centered around data processing. I previously used Perl for just about everything (although I've used Python & Ruby also), but started to broaden my programming horizons recently, and after a grand tour of what was on offer I settled on Racket as my language of choice for the more complex end of the scripts I was writing. I'm finding it easier to maintain (and especially refactor) complex scripts in Racket than I did in Perl (or Python or Ruby), and the increase in performance is substantial when processing huge data-sets. One current weakness of Racket here is the relative lack of specific libraries for bioinformatics, but most of my code doesn't need any anyway and when it does I revert to Perl.
I'm also excited about investigating other areas of the language, especially Typed Racket, as static typing is something I haven't really utilized so far.
In general, the more I learn about Racket the more I admire the quality of design that has gone into it; everything seems to be extremely well thought out, not just from a theoretical perspective, but from a practical one too.