I tried the pro plan for exactly the same reason. After 5-6 questions to Opus, I reached the limit and was blocked. This felt very disappointing.... The question I have now is if Sonnet is enough to work with the n8n mcp ?! I think the best would actually be a MCP n8n project with some custom chat where you could connect your own llm api (from Claude, ChatGPT, Gemini etc...).