I am mostly interested in playing full ASL, but I will play SK scenarios, mostly as a way to get more players into the system.
And I don't know how many ASL scenarios use the SK boards, but I am very happy with the fact that a player who buys the SK system, and then tries to move on to the full game, doesn't have to throw away his boards and counters: they're already the real thing, and perfectly usable for full ASL scenarios. If it means that "ASL only" players will have to get the occasional single board to be able to play their (already too large) scenario collection, I think that's an acceptable evil.
(Using ASL boards for SK scenarios is typically more difficult, as they will often have terrain that is just undefined in the SK system)