Company Directory Sub-Categories

[jskphotography]

I've been having a play with CompanyDirectory and trying to use Hierarchy and Categories to provide the desired result. My problem is that I have many categories (100+) for good reason, I would like to have groups of categories but the catch here is that a single company can belong to many categories. This 'many-to-many' requirement makes the hierarchy option unsuitable since a company can only sit within the hierarchy at one position.

I may be missing something obvious here, perhaps continue to use categories and assign numerous categories a group 'tag'? Anyone got any advice?

Much appreciated.