Use, ProprtyInstance--> getFullyResolvedPropertyValue, if property is part of property instance.
Use, ProprtyClass --> getDefaultValue, if Proprty is part of Property class.
Just one note - leave out any folders defined in the property dictionary.
What folder you want to leave out?
Do you mean look for any specific folder?
A bit cryptic, it was just meant as a note to anybody else using the PropertyInstance getFullyResolvedPropertyValue command.
We have a folder structure under System Object in the Property Dictionary, which are "Built-in Property Classes" and "Custom Property Classes". When using the command above you need to leave those out of the class argument.
This may only make sense if you have to same setup.