The ztrons might be better compared to the cx line in terms of measurement using the DTCD but it does not mean the sound will be better (in your system). Only you can decide that.
There's also a possibility that the true potential of the ztrons were impeded by the rest of the system using the cx line. Perhaps a better comparison should have been an all cx line against an all ztron line. Unfortunately there weren't enough ztron power cords to go around to make that comparison possible.
If possible the best thing is to try both lines. If you prefer the cx line in your system then you are in luck since they are probably going to go down in price.
There's also a possibility that the true potential of the ztrons were impeded by the rest of the system using the cx line. Perhaps a better comparison should have been an all cx line against an all ztron line. Unfortunately there weren't enough ztron power cords to go around to make that comparison possible.
If possible the best thing is to try both lines. If you prefer the cx line in your system then you are in luck since they are probably going to go down in price.