First, a small defense of Racket. Racket has a small core relative to its apparent size; most of the bloat is in optional library code. All the fancy special forms for pattern matching, classes, contracts, etc are just optional macros from the libraries, and everything eventually expands down into this rather small core language:

https://docs.racket-lang.org/reference/syntax-model.html#%28...

The default `#lang racket` is a big batteries-included language including all that stuff, but the core `#lang racket/base` isn't very big. I always program in `#lang racket/base` and pull in just the libraries I need. For me the most beautiful part of Racket is this juxtaposition of a small core language and a big extended language implemented through a standard library of macros.

You can also install a distribution of Racket that leaves out bloat like DrRacket, Slideshow and the teaching language packages from the release variants page: https://download.racket-lang.org/releases/6.8/

As to your question, Beautiful Racket appears largely a guide to the language extensibility features that are specific to Racket and not shared by other Scheme systems like Chibi. Things like the `#lang` system, lexer library, and syntax highlighting integration in DrRacket. I imagine you'd get the most benefit out of it by working through it in Racket, and subsequently thinking about how to apply the ideas in other systems like Chibi.