Additionally, if there’s more “knowledge” of the code and best practices and such baked into your model, it has to spend fewer tokens reasoning about it or even potentially looking it up. I think even one web search to retrieve additional information not also in the model will probably blow up any supposed benefit you’d get by a slightly more token-efficient language.

That could be mitigated by using a much smaller non-reasoning model for searches and reading. There's no reason why a search should take loads of tokens.