I am, yes. I'm more familiar with their researchers, but I know (or have spoken to) people across different functions there. They have security engineers who earn over $1M/year (for one example of something which isn't usually "front office"). For Jane Street it's about impact: if you substantially improve something at the firm, you share in the spoils.

That doesn't mean literally everyone who works there is rich, and the quants will do better relatively speaking. But in the sense of engineers being second class citizens: no, I wouldn't say that's the case at all.