The 30mm lens has been on my B&H wish list for over a year now.
On darker rides, I've been using the 50mm f/1.4 lens. You're right in that the lens may be too close for Spectromagic. However, it especially comes in handy on rides where the characters are just slightly further away (like It's a Small World, Pirates, Gran Fiesta Tour (in Mexico at Epcot), Snow White's Scary Adventures, Winnie the Pooh, Splash Mountain, etc).
Whenever I use my 50mm lens, there's always 1 particular spot where I always wish I had a 30mm lens instead. It's at the end of Haunted Mansion, right when the doors open to reveal the Hitchhiking Ghosts. I always feel like my 50mm lens brings me too close to them, and we pass them by so fast.