Yes, you need their core datasets.
Background reason:
When CMP first stated that they were going to do PCGen datasets, there was a vocal minority who proclaimed the CMP was going to "steal" the work of the PCGen data monkeys. So, in order to not be accused of this, CMP did the core sets from the ground up. Their PHB, DMG, MM datasets differ from the PCGen SRD/RSRD datasets.