Might I be nosy and ask what Scheme environment(s) you used in these production deployments? Thank you.
I've used:
1. Chicken Scheme for development, Gambit-C for release.
2. Custom baremetal Scheme based around the design of PreScheme and Microscheme. Implemented using Gambit-C and some of it's unique features. They had 8,16, and 32bit variants for half a dozen chip makers. (100% proprietary, and any real details covered by an NDA).
3. Racket for development, Chez Scheme for release.
Racket isn't quite Scheme, but it's IDE makes development so much friendlier, that I'll jump at the chance to use it. However, an amazing compiler is needed for release, at least to meet the standards I tend to need to aim for.
... I've done that too.
It's not a blind 'compile & release', but some compilers optimise better, others are faster. Wildly differing behavior is very, very rare in my experience.
Tradeoff being you have a more limited language subset, and may need to adopt only one compiler in the future.
> I'm assuming you used the R6RS language in Racket for compatibility?
Sometimes, more often r5rs, as that's what Gambit-C aims for.
The fewer interruptions to a programmer's flow, the better.
However, on release, performance, and binary size, often matter, so go with the best.