This would be awesome! We use progression steps like progress through the funnel so this would be a very useful way to see where campaign members are in the cycle. The out of the box program performance report isn't terribly useful because as soon as you update a progression step for a contact in a given campaign, they become a member and you don't get any more information until they achieve a "success" step.
It would be nice to see something that shows # of prospects in each progression status for a given program. The sum of all the groups would equal the total membership of the program (this would require removing/adding them from each group as they engage w/ the program).
I tried all morning to do this in RCA before I realized it wouldn't let me. That was a disappointment. It's not even a functionality in regular reports. I see this as a significant flaw because only being able to show the "success" isn't valuable all the time.