Thanks, Sandy, for your prompt and informative reply.
I have just made up some fresh "PMC" that was one of your earlier formulas. I mixed it without bromide, and with 25g/L metol, and got a healthy 200 speed out of HP5+.
As soon as i can, i'll mix up some more real pyrocat-HD with phenidone and bromide.
Could you explain why bromide gives more speed? Would varying bromide change acutance effects? I'm particularly interested in semi-stand development with half-strength pyrocat-HD. Even my faulty batch gave me brilliant, lively sharpness.