In case it interests anyone, I built a document editor + GPT and updated it to use text-davinci-003: https://github.com/typpo/arkose/ If you want to try GPT-3 but don't have an OpenAI API key, I've set up a quick demo here until I hit my billing cap (normally users would supply their own API key): https://arkose.pages.dev/
Shameless plug: We've just updated to davinci-003 for the AI Assistant (MacOS/iOS/iPadOS only) in Craft[1]. Free accounts have a handful of requests included if you wish to try out the new model on there as well.
[0] https://beta.openai.com/docs/api-reference/completions/creat... [1] https://craft.do/