Author here! Funny to see this arise now, I shared links to the project a number of times but never got much interest here. For what it's worth, I would (and should!) update that page, but the choice of s7 has worked out really well. I now also use it in a WASM context, which is great. The fact that I can easily use the same scheme implementation anywhere I can run ANSI C has proven to be a real advantage.

Happy to answer other questions.

For people interested, I will update that page today with thoughts five years on.

TLDR: still really happy with the choice!