Luigi, thank you, very much, for your kind words about my work.
I have started with the Analyzer Pro, which I have replaced with the StopClock, almost straight away. I just did not have the need for the Analyzer part, but I wanted a good split-grade system, with f-stop timing. StopClock was better than the Analyzer in that respect, more flexible, and I found it easier to use. However, a while back, I pretty much quit split-grade, and I am back where I started, working with set contrasts. I still burn with various grades, almost always. Occasionally, I will use ZoneMaster, especially when changing enlargement ratios. If, however, I was going to split-grade again, I'm sure I wold use the StopClock, it is a fine instrument. I wish I could compare it to Nicholas's device, but I have no experience of it.