Conny,
Thank you for you reply!
From my project experience, when we use cumulative flows on stories, we focus more on the unit of Plan Estimate Total instead of Story Count. There are not many Rally APPs using Story Count actually, comparing to APPs that us Plan Estimate Total. Story Count is really not a common used unit for story cumulative flow. That's why I'm suggesting if there could at least be an option to select "Story Count" or "Plan Estimate" as the unit to use.
I really like this APP, as it give an alternative to show Cumulative based on Kanban Status. Based on Story count, somehow I think that's not helping to increase its popularity.