This is the second time Bencode's been mentioned in the context of Son. I didn't know about it before, it definitely looks interesting! However if you're sending data to a service that only accepts JSON then it's obviously not an option.
Fair enough. Backwards compatibility is useful in some contexts.
By the way, I love that Bencode is bijective. That's a really nice property for a serialization format, and even though I don't mention it on the README it's one of the goals of Son.