^This is me... have always downloaded demos via an external source (rbn releases or dlcquickplay, usually) then played the demo and bought from the menu that pops after the demo ends.
Couple more things:
While I've never been overly bothered by the dlc load time when booting the game...having to sit through it twice simply because I wanted to buy a few more songs is definitely pushing it
Finally, so I can queue regular dlc purchases through the website marketplace, dashboard marketplace, stand-alone RB store or in-game store... RBN songs? only the in-game store...hard to believe this won't impact sales.