We actually had only 4 Legendaries (one was a Hyperspace) in a total of 9 Prerelease packs in yesterdays Event. I also thought that it is usually at least 1 / Prerelease so it was a bit dissappointing, but cant wait to open my displays next week.
My 6 packs had no decent bombs and a pretty awful selection otherwise, so pre release went terribly. On the plus side there was a showcase in there so at least I lose in style :D