Note that James Griggs cites Schaeffer's 1973 Patent (as Sonaqua Inc.) in the patent for his own (much simpler) water heater.
A lot of this stuff has been around for a long time. However, the relatively low effectiveness of the various implementations makes it easy for people to dismiss them as being "bogus", without looking any closer at the possible principles behind them.
JedRothwell had the opportunity of witnessing and taking part on the evaluation of Griggs devices, he has posted about it elsewhere in the forum, if I recall correctly he has a strong view that it was subjected to supression by academic politics, as CF did.