The original data sheets that came with Dixactol gave instructions primarily for two bath development with an after bath to enhance the stain. I tried this method using approx 3.5 minutes per bath and thought the negatives lacked density. About a year later I read Barry's "Supplementary notes" on his web site and, following experimentation he, quite openly, said that the recommended use was single bath with "partial stand development" i.e. continuous agitation for 30 seconds then one inversion every two minutes. Further researches showed development times of between 7 and 9 minutes (if memory serves). I also downrated my films by 1/2 a stop and using the single bath method got far better negatives as a result.
One poster asked why Barry did not publish the formula. My answer would be - why should he? He was trying to make a living. You can only earn so much doing bespoke hand printing and giving workshops. There are many developers on the market whose formulae have never been published.
I also suspect that further iterations of Dixactol show that he was continuously evolving and improving his product.
Personally I don't think he was a "snake oil salesman". My brief correspondence with him led me to think of him as a genuinely helpful man who was passionate about his art. There was certainly no mystique in his writings. As a supplier of photochemistry he was relatively new to the market and I think still refining his products. Sadly due to his untimely death we will never know what he could have achieved.