Obviously talking my own book here, but we've helped dozens of customers make the transition from prompted GPT-4 or GPT-3.5 to their own fine-tuned models at OpenPipe.

The most common reaction I get is "wow, I didn't expect that to work so well with so little effort". For most tasks, a fine-tuned Mistral 7B will consistently outperform GPT-3.5 at a fraction of the cost, and for some use cases will even match or outperform GPT-4 (particularly for narrower tasks like classification, information extraction, summarization -- but a lot of folks have that kind of task). Some aggregate stats are in our blog: https://openpipe.ai/blog/mistral-7b-fine-tune-optimized