I think it depends what you're trying to accomplish when lunging. Everything you tell your horse is through body language, aided by a voice command...while asking her to whoa, what's your body saying? Are you in an arena or round pen?
I do things backwards from Spirithorse. I find it easier to lung at liberty than on a lead...I'm constantly fumbling with the length of it and it takes away from what I'm trying to ask my horse to do. I personally see that as a step up from at liberty. Then again, I only lunge in a big round pen. An arena would be alot harder to keep their attention.
Everything else I agree with though, she sounds as if she's only getting worked up as opposed to warmed up. I'd work on walk/whoa transitions, when she's confidant to do that add trot, and so on. Definitely keep us updated on how things work out!