Hi Mark,
I'm a former SW user and I used their equivalent all the time. I was an easy way to 1) control all custom properties, and 2) have a pull down list available.
We used custom properties to help distinguish commodities and other commonly used parts.
The propseed.txt file has the advantage of including categories, while the SW version only had a single list of properties.
Hope that helps.
John Graham
Applications Specialist
Designfusion