I think one of the key problems here is depending on the system prompt and the prompt itself the LLM will take on completely different personas, but I think OP

I think one of the key problems here is depending on the system prompt and the prompt itself the LLM will take on completely different personas, but I think OP very correctly takes a look at "well then how do different models handle the same system prompt" and look at differences there. I think in general though the system prompts themselves and the effects they have are far more interesting than slight differences between established models.