Thanks, fellas. From the looks of things, the Z-12 parallels a lot of the ingredients in MST's Somnidren product. I'm looking for better sleep, not necessarily GH benefits. But still, Somnidren costs less than Z-12 and has the advantage of being designed to stack with ZMK.
At the very least, this will give me a chance to compare both (Somnidren and Z-12) side by side.