This is all very interesting and intriguing. Unfortunately, I can not add to the general knowledge or experience, yet. I purchased a StopclockPro and ZoneMaster II from a list member through the APUG Equipment for Sale forum. ( Will probably arrive this week and I am in Denver at a seminar until Friday :-( , so I have yet to tackle the calibration and practical learning curve.)
I had been researching f-stop timers and analyzers, (I am a Jobo product fan, in general, but have never been able to receive "value" from my Comparator to move from step strip iterations). The RH Designs site is very informative and I decided that the products would meet my needs. I downloaded manuals to read and hopefully predispose aging brain cells to "get it!" quickly. Additionally the site has a user written guideline for calibration.
I emailed Dr. Ross with a question regarding pyro negs and received a prompt and courteous reply. I am excited, but, perhaps, a little daunted by the posts regarding the calibration of the analyzer, (ZoneMaster II). My experience has been that responsive vendors with websites rich in customer oriented content generally make great products. I am positive that this purchase will reaffirm that experience.
Thank you Dr. Ross for posting to the community!