BAML sets system as the default message in its examples. Usually I put instructions into system and then data into user message. Have you seen any difference between putting everything into system vs splitting into system and user?

In my experience there has been some minor behavior differences, depending on the prompt, but most of the time they pretty much work the same way. Curious about what others see.

same, except when i accidentally skipped system and had 2 user. It lead to some crazy bugs