Both systems are good, and all that is needed is good samples.
Composition should be stoichiometric, structural property to be good, and sample must have a high resistivity, and proper electroding on both faces. If these conditions are met, I am sure, both the systems will measure the properties to the same accuracy.
The Precision Premier II, Radiant’s most advanced tester, has the largest envelope in terms of frequency response, voltage range, and accuracy of any ferroelectric tester in the world.