I have only used virtual load cases with lateral force on a single diaphragm. The program allows you to enter other loads, but I've never had a good reason to do so.
I ran a simple test here and I don't think the scale for the load pair actually does anything. I get the same results in my test using 1 or 20.
I think it was originally implemented so that users could linearly scale up the various participation values you see in the member view/update dialog in case the reported values were too small to offer enough significant digits. I'll try to get confirmation on that point.
The virtual work analysis in Ram Frame is one of those features that I think can be very useful, but most engineers don't use it because it's not a code requirement. I would love to hear more about your building and any other feedback you have about it's usefulness in optimizing the structure.