Regular user. For useful tasks, how much of a difference does the Pro plan make?

Nowhere near as good as ChatGPT 4o or Claude (in not one case have I had it outperform those other two), but at least it can do math and data science correctly most of the time compared to the regular model.

I use it as a secondary when the other two are chewing on other tasks already.

I only own it as I am an outrageously heavy consumer of LLMs for all sorts of little projects at once and they all seem to pause one window if you use another.