I filed a feature request today to have the ability to backup Property Groups from the UI and CloudClient in vRA. For organizations that use many Property Groups in a modular fashion across their vRA environment, they become an important artifact similar to blueprints and need to be protected against loss of all sorts. If any of the VMware employees see this and also think it's a good idea, perhaps they can help move that request along. Any others from the community that feel the same way, please chime in!
I don't see any commands associated with exporting property groups in the command line options? I exported content using the id from 'vra content list' and the output consists of 2 yaml files neither of which contain property details besides the hame of the group.