It's not just an Epi disease, Gibson's knowledge about what it brings out is half-assed too, especially as regards limited runs. Somehow, I can't beleive that the people at the bench decide on a daily basis whether they do a ltd run or not, so it must have something to do with available inhouse-information not being properly compiled.
That said, there is one person who is actually pretty good with Epi stuff and that is their current President. No joke. Go to the "Talk to Henry"-forum on Gibson's official site and there the Epi boss, who seems to be a real likable guy, has his own thread. And he even answers regularly.