JR, I'm perplexed by your comments regarding Maeda-san. You go to great lengths to mention how he has impressed you with his koi keeping prowess and how he was employing fairly normal methods in the nineties. But after doing so you seem to discount his current methods as some technological dead end or wrong turn. Perhaps what he is doing now isn't helping as much as we'd like to think, but it certainly doesn't seem to be hurting. And he is going to considerable expense to do follow this path. Plus, how do you explain Mike's report regarding Hikui in Maeda's non-Bakki system?
Regarding the science behind it: nice to know but I'm OK with something just working.
Once we know the science we can make the stuff cheaper, right?! Or at least know WHY it is so expensive. Mike has provided many examples of how the stuff was developed and the research that went into it. This doesn't appear to be so kind of magic dirt or snake oil, especially since the guy selling it is a well respected breeder and really does seem to be putting his money where his mouth is.
Regarding 'open' system. The water changes reported here seem to be a max of 10% per day. Well short of the 100% per day I've seen reported of Maeda's ponds. Surely 10% a day is not too unusual. How much do you change in your ponds during the season?