Agreed with your workflow and yes I have done that with other projects.
I’ve been testing the Flex demo and so far I love it.
However, I have to say the steps you suggested would have been just as rewarding but the trip would have been long.
I did something similar using Maya with vertex on polygons and then exported the outlines and matched it in AE. It was more of a fluid result but the process of converting to layers in AE was way too long to deal with.
Still a fun experience but not as easy as a plugin.
Flex has its shortcomings but that could just be lack of experience with it.