Yes, as a matter of fact I had the RH Designs StopClock Pro & Zone Master II that I used with a Zone VI V/C Head.Have you considered the Analyser pro from RH Designs?
I sold them to another forum member. I got a deal on the Beseler system and had no use for the StopClock Pro timer anymore. I figured that it would be easier to sell both the timer & the Zone Master together, so that is what I did.
(I never did get around to calibrating the Zone Master)
So now I'm looking at the Splitgrade system.