I've read your post three times and feel that that there is more than one issue to deal with. You seem to be obsessed with a dislike of grain. Perhaps the need to eliminate grain is beginning to dominate your thinking rather than the real reason for making photographs. You said in your post that you don't want grain as it's not your primary way to make art, surely art is not about technical matters, it's about vision and a need to express and communicate. The excellent recent debate about vision in another thread is worth reading again.
I went through a similar dilema a few years ago when I downsized from LF to 35mm in order to persue a documentary project that was impossible to do in LF. Grain became the issue when I made the first batch of proof prints for after LF, 35mm prints from Neopan 400 had grain like golf balls, at least it looked like it to me. John Blakemore, a British photographer, helped me put it into perspective by making me think of the project and expressive images. I now happily make 16 x 20 prints from 35mm Tri X developed in my favourite developer. (I'll mention that later) Yes I can see the grain but it does not intrude at all. Please don't take what I've just said as an attack on your thinking or likes and dislikes, I'm just trying to divert your thinking to help you decide direction. It seems to me that you should be thinking about the images floating in your head and not carrying the burden and obsession with too much grain.
Your posts always show that you think very deeply about your photography and clearly, you have carried out many tests to try to arrive at the best film/developer combination. Any combination that I, or anyone else suggests can only form a starting point for you for we are all different. I have to say that I'm usually reluctant to suggest any specific combination in a forum situation for I think that there is a potential for leaving the person who asks the question in a state of total confusion, but perhaps it's time to break my own rule.
I know that you have used some if not all of the staining developers, perhaps hoping that you are able to arrive at a situation where you have only one developer/film combination to do all things. I have read claims that staining developers are just that and I have to disagree. Many years ago, long before staining developers became fashionable, I considered using them and was told by my mentor that I trusted, that they increase grain but that it is masked by the stain. I don't wish to start a flame war with that statement but my experience with some of the staining developers currently available bears it out.
My suggestions re film/developer combinations are to work with Tri X and either ID11 or D76 and use exposure and development to control contrast and highlight detail. My own favourite combination is Tri X and Fotospeed's FD30. I would also consider Ilford Delta 400 in either ID11 or Ilford DDX. I noticed that you use D23 to help compensate for guessing the exposure, surely assessing the light and subject and making the correct exposure and then giving the correct development must be a priority. In fact, any form of guesswork in your exposure may be the reason for evidence of grain in your photographs.
Thank you for sharing your concerns and problems Frank, I hope that I have not offended you with some of my observations and comments.