Thank you. Not confusing at all, I don't think, and vey helpful to me.
My understanding:
Benefits of demand valve: (1) It resolves the issue of waiting for the bag to fill (other things will do that, too, such as a reg with the necessary lpm, but DV does it brilliantly); (2) no waiting, no fiddling: It's there, it does what you need when you need it without you having to think about it or play with dials, which is a particularly big benefit for quickly addressing nighttime hits or in other circumstances (e.g., in the car); (3) it can save some O2 in some circumstances. I would add what I mentioned before -- that at least for my daughter, there are psychological advantages from having no bag and having the "ideal" delivery system, and any psychological benefit in this situation is not insignificant.
Disadvantage: Cost. Similar or equal abort times can be achieved with a reg that will cost far less, as long as that reg has sufficient lpm to be sure the bag is always full for the next inhale -- recognizing that a reg is imperfect compared to the DV when it comes to the "no waiting, no fiddling" and possible other less tangible psychological benefits.