Thanks for your ideas! Unfortunately, I can't change the categories for this upcoming version, but I agree that it would make sense.

I recently added a new method on the SDS dev server (sds0), which returns the account count for a specific VESTS range:
https://sds0.steemworld.org/describeMethod/accounts_api.getAccountCountByVESTSRange

For example, to get the number of accounts owning between 10,000 and 99,999 VESTS, you would call it like:
https://sds0.steemworld.org/accounts_api/getAccountCountByVESTSRange/own/10000-99999