Ed Oden,
When a redan transitions from being slightly down hill, to where it becomes a "drop shot" hole, I think it loses its "true" identity.
I don't know what the differential in the putting surface, and remember, there's a huge difference in the elevations within the putting surface at # 4 at NGLA, and the tee are, but, from a playability perspective, they're slight (de minimus).
I believe "slight" elevation differentials where the green is below the tee are acceptable in terms of the hole retaining its "true" redan classification.
Anything where the green is elevated above the tee is preferable.
Once the hole takes on a "drop shot" approach, it loses its identity as a true redan.
That's my definintion and I'm sticking to it.