I remember you were still working on the WP support for category hierarchy mapping.
I think that the most important thing is that we get to organize the subcategories in the PT installation to sort through the product categories and to have a tool to structure it. If these subcategories are not shown as actual subcategories in WordPress is actually not that important if we are talking about drilling down and narrowing down search results, as the filter dropdowns would show only the few relevant categories for a specific search anyways and whether they are subcategories of a parent or not is actually not that important as long as they show.
The best and probably a lot simpler way to make this useful, would be to treat PT subcategories as normal categories in WP.
I would like to know your thoughts on that. Maybe that could be an intermediate release. Or maybe I am already losing the big picture zooming in too much on my problems.