Is it? I'd love to see a breakdown of what classes of information can be gleaned from profile data, and how much of an impact each one has in isolation in terms of optimization.

Naively, I would have assumed that branch information would be most valuable, in terms of being able to guide execution toward the hot path and maximize locality for the memory accesses occurring on the common branches. And that info is not something that would be assisted by more expressive types, I don't think.