Good response, I also started ACCA without knowing about CIMA until a few months ago. I have 4 papers left in Fundamental Level (F6-F9 remaining) and I have been struggling with whether I should make the switch from audit to management accounting.
I think CIMA offers additional skills in the areas of risk management, operations and strategic management that are not offered in ACCA. There is no waste of time. Having both Certifications will enable you to add real value to your organization. I say go for ACCA then go for CIMA if that is what you really want. Let no one stop you.