@Wakibaki: First off, I honestly had never seen your schematic earlier. It was posted on websites I don't usually read. Had I seen it, I wouldn't have posted mine since yours is working better. I'd rather have contacted you about it. At the time of posting, I really thought that this particular mix of parts hadn't been done before. Clearly I was wrong.
@all: Secondly, I should probably have linked to the RKV which was my main source of inspiration. But since I had just posted a thread about it, with proper references, and that the posting of the schematic was, in my mind, just a continuation of it, I must admit I forgot. That much I'm willing to confess. Please accept my apologies for a moment of carelessness.
Then, to answer the last direct question, I didn't credit Broskie because the schematic I posted doesn't make use of his material. It is the biasing scheme of the RKV I used, not his. The one thing Wakibaki gives credit to Broskie for is exactly the one thing that makes our schematics quite different. Ironically, it is also the one thing that makes his superior.
When I wrote I started with Tubecad, it is literally that seeing that schematic made me think I could extend the "variations on the rkv theme" to electrostatic amps. Broskie's basic hybrid building block is just the same as the rkv (a tube controlled by an opamp wrt gain but also operating points, especially plate voltage). So I tried to see if I could do it somehow differently.
Finally, there aren't that many way to skin a cat. I don't pretend the schematic I posted is something revolutionary or even new; all the elements are well known if not trivial. There aren't many tubes able to sustain the voltages needed and even fewer high voltage depletion mosfet with low capacitance. The controversy between srpp and resistor loading is spread over so many threads, who am I supposed to credit ?