Anybody know if it should be possible to use a Summary Search in a WF to drive a Set Field Value action? I have a saved search on items with criteria that pull 200 records, and then summary criteria that whittle that down to the 31 I want my WF action to apply to, but from my testing it appears that if I use my search as the condition for the action (I can't just use condition builder due to the specifics of the requirement) the WF action is completed on all 200 records in my search, and NOT just on the 31. Am I missing something obvious or does WF based on searches just not work this way?

I would probably go for scripting in this scenario. Alternatively if that's not an option, you could build a saved search field, and use another workflow to pass that field into another field. Then use that field as your criteria for your workflow.