I saw a Saturday matinee in April, and both Teal Wicks and Katie Rose Clarke were out. But their standbys were really good, so I think you'll enjoy the show regardless of whether you see Wicks/Clarke or the standbys.
As for Behind the Emerald Curtain, keep in mind that it's not a backstage tour. I have not done it myself, but I think you'll find it enjoyable and informative.
"What was the name of that cheese that I like?"
"you can't run away forever...but there's nothing wrong with getting a good head start"
"well I hope and I pray, that maybe someday, you'll walk in the room with my heart"