I'd agree to this whole heartedly. At first glance (if I'm understanding your implementation correctly), it appears like you're already going to use up the same amount of space a buffer would anyway. In this case you're just tasking the LUA best practice, but making it a feature within Redis itself.

Regardless I think you're really onto something that people want. There's going to be a trade off one way or another, but the Redis community is all about speed, so the faster and more efficient you can do it, the better (: