You completely missed my point, but in all cases, I believe that Tony was asking to summarize your thoughts, not summarize mines.Absolutely, SINAD is the most informative singular condensed metric I've come across. Nothing sets the stage for expectations better than it with respect to fidelity concerns. Alone it obviously isn't as imperative if you have a constrained set of concerns (like if you're a passive speaker enthusiast, you have far bigger troubles with respect to power output almost always a thing that is lacking, and perhaps like PeteL, this is a more informative metric for your buying needs). But across the spectrum of all audio output devices, SINAD hasn't really been topped as an aggregate metric as being the most informative for setting the stage of what to expect with the rest of a device's fidelity preservation capability.
PeteL disagrees with me in totality on this claim, he takes SINAD to be quite literally meaningless in all instances. Since there was pedantic detail in our conversation, I don't he means it's actually definitionally useless, but obviously at the very least, he does consider it useless from an informative value perspective with respect to his concerns it seems.