Both products are easy to use for straightforward timing. The Analyser has an ergonomic advantage inasmuch as it's an all-in-one unit and you only have one keypad to think about. For straightforward printing from a lot of negatives it's probably the way to go. But if you want to wring the last drop from a negative, the StopClock offers the convenience of programming a sequence of exposures so you don't have to remember them all in the dark.
I've had a ZM and stopclock pro, purchase in 2003. I have never had good luck with the ZM but I would't trade the stopclock for anything. I think that the ZM is too computer like for me and I just have not devoted the time to learn it's functions.
I can see that it is probably one of the best combinations available and will knock my own lack instead instead of the instrument.