As Parodites pointed out to me, all metaphysics raise up a single image of the perfection or Totality by which everything, and I mean everything, is then reinterpreted back in terms of that Totality and single Idea. Nietzsche's will to power is perhaps the best-yet formulation of a metaphysical idea, probably because Nietzsche reverses traditional metaphysics and kills God, therefore finds the will to power as the last remaining metaphysically-possible notion. Metaphysics works because it gives us a means of catharsis and freedom over what had formerly limited or blinded us, as how I've talked about how free will is simply a kind of determinism that is capable of surpassing those causes which, prior to a given threshold of freedom attained, would have acted as absolutist causes and blinders for us but now by virtue of this new freedom (deeper more complex determinism, our minds, understanding, emotional catharsis, etc.) can be either suppressed or parsed out and dispersed this compelling cause power over us.
It may be the case that there is no possible higher metaphysic than the notion of will to power. In this case the will to power is the metaphysic of all metaphysics. For me this is very useful right now because it gives me extreme objectivity, catharsis, freedom, and the ability to synthesize contrasting and different perspectives in thought and emotion within myself. But to what end? My own self-valuing, edification and sanity, surely. These are very good ends for me or for anyone else, and the will to power is therefore justified as a psychological subjective method over probably all other metaphysics ideas and systems.
Interestingly, the form and type and scope of "freedom, catharsis, edification, etc." to be had by any one metaphysical method or idea depends entirely on that idea itself, on its content and formulation, on its 'meaning'. New and different types of humans develop under new and different metaphysics. Nietzsche did not go beyond metaphysics, as he thought, rather he found the "metaphysic to end all metaphysics". This isn't "bad" per se in so far as metaphysics is useful and still necessary, or at least in so far as an individual person such as myself finds far more meaning and value in this one "final metaphysic" than in any other competing metaphysical ideas or systems.
But is this really the end of philosophy? Parodites says no, and shows how we can go even further than even the best possible metaphysics. I am going to keep my will to power method for now, while also trying to move toward the truly "post-metaphysical" method that Parodites has created. I will continue to use and value Nietzsche and the will to power until such time as I find and encounter something that cannot be beneficially reinterpreted or used within the WtP/Nietzschean frame. So WtP/Nietzscheanism is something I posit for my own gain, a self-value in a purest sense. It is unclear to me how to live as a psychological subjective selfed entity without at least some sort of "metaphysical" grounding. Perhaps the perfected philosophy (Parodites' work) is still too new to have yet created a corresponding psychological subjective type and 'self' able to embody that philosophy in and as an individual human being.
It seems that his notion of mens heroica, or maybe the eroto-daemonic, hold the key to how to surpass all metaphysical need on all levels of our being. I'm not there yet, but can intuit the way forward.