Another point that could be added to your list is: 5) mistakes are made. Putting together a really good sounding stereo system is to some extent a trial and error process. Some of my purchases-- both new and used have simply not worked as I had hoped they would, so I sold them, but they may work very well in someone elses system.
I have come to the conclusion that in-store demos are almost a worthless exercise because the room is so important to sound quality/character, as are component and wire inter-actions, and of course set-up is critical(sorry dealers, but it's true).
So, one way or another, you have to audition each piece in your own room and system. Some dealers will allow home trials, but many either don't have what I want to hear, or simply won't let me take their demo for a few days, or they have too many "conditions" attached to home trial. I'd rather buy used, and if the piece doesn't work out sell. Cheers. Craig.