When comparing Gambit vs Chez, the Slant community recommends Chez for most people. In the question“What are the best scheme implementations?” Chez is ranked 3rd while Gambit is ranked 5th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Can be easily embedded into an existing C/C++ codebase
Gambit has a built-in compiler that generates C code, which then is passed to your system's compiler which in turn compiles it to native code. This makes it easy to integrate Gambit into existing C/C++ projects.
Pro Actively maintained
The maintainers are continually working on improving the implementation in a variety of areas: multicore, modules, backends for x86, ARM, RISCV, JavaScript, Python, Ruby, PHP, Java, and go in addition to the current mature C backend.
Pro Good performance
Gambit is fast/efficient, you can see benchmarks here.
Pro Very portable
It is very portable as it has no external library dependencies. It will build as long as the platform has a C compiler.
Pro High performance among Scheme implementations
Pro The only Scheme compiler to produce executables directly, without first compiling to C
Pro R6RS
Cons
Con Lack of SRFIs
Gambit natively implements few SRFIs. Additional SRFIs are available through the Black Hole and Snow third-party systems.
Con Documentation is poorly formatted
The Gambit documentation directs you to further resources, depending on what you're looking for. Because things are separated into different places, it can be difficult to find what you need.
Some documentation is only available in HTML or PDF formats that are hard to read/follow.
Con Limited third party lib and resources
Con Not available as a Debian package
Package chezscheme is available for Debian buster & sid, but not for stretch.