You are right, version 2.0 lacks ratings, etc. Version 3.0 will have ratings, tags, flagging, and filtering.
The data is stored in the application sandbox, so it will get backed up by any program that backs up the home folder. I just double-checked by going into Time Machine and accessing (Home)/Library/Containers/com.gentlemencoders.RAWPower. All of the document data was there.
I plan to add an export function to make it easier to archive this data in the future.