Is it true that there is not much difference between free and affordable models? And, unless you are spending $2000 per month, you are not really leveraging the industry standard coding agents.
Anecdotally, yes there is definitely a difference. Even e.g. Haiku (cheapest Anthropic model) vs gpt-oss-120b had a big difference in quality and syntax issues when I was testing them for DSL generation. Granted, that's a little different from generating a popular language with lots of training data, but you could consider it a proxy for "learning" new concepts outside of training.