As zab mentioned, the movement has been away from the weeds regurgitation (I can't say that has happened, only that they were trying to start that move when zab and I were still in the FRS). I have always been a big fan of knowing why when x breaks, it effects y and z. And if you close this circuit breaker in the EP, why you are doing it. Sometimes (and I use this lightly), asking the limits or weeds question can help to ascertain whether the upgrading pilot understand the system in question, or whether you need to break out the book or take that walk around the plane to discuss in greater detail.
I'll be the first to rally against fuel pressure numbers and micron numbers, but there is a difference between a Natops check and an upgrade. Natops just checks to make sure you're a safe and (hopefully) competent pilot, but it doesn't guarantee you have a full understanding that you could. Where as some sort of A/C and/or FCP qual allows for more in depth questioning. A bud of mine (who lurks on here some times) had a battle damaged hydralics EP on his HAC board. The O-4 would show different caution/advisory lights (that he pre-scripted) and have him talk through what was damaged and what he could do about it. The fundamentals come right from our Natops and is a system you always brief, but the questions were above and beyond since it was a board. I thought it was a clever method, especially should our community EVER get to play in anything "dangerous."