...also on a second thought I guess the alternative approach with the 3rd level subcategory mentioned above would not work, since I would have both categories and products under the same parent category (i.e. I would have a "category-product" like flower-pot "deco" which would contain product versions as individual products, and other products under the same parent category).
Also, as I have stated above, beside each attribute, my customer wants to show dimensions, sku number, price and weight, with the site visitor being able to pick one of these product versions.........I want to add a search by sku feature to the site
(i.e. the site visitor must be able to do a search by sku code, even if that code belongs to a specific product attribute/product version)

Any suggestions ?