Why are the product fields controlled through ../admin/store/settings/products/edit/fields instead of cck style ../admin/content/types/product/display? It seems like it would beneficial to be able to use the cck field setting to hide/show fields on teaser and body differently. Additionally, it would be nice to have some fields on certain product (content) types and not others. Is it too late in the game to be talking about this or could custom CCK fields be created that referenced existing tables and functions?
The biggest problem I have with using CCK for product fields is that Ãœbercart would not have any control over them. Many other modules, particularly uc_cart and uc_order rely heavily on the fact that products have SKUs, prices, and weights. You can't choose just some CCK functionality; it's all or nothing. And I just know that somebody would delete those fields and break Ãœbercart.
If there was some way to tell CCK that the module data should be treated as permanent fields, I'd be all for that. I haven't been keeping up with CCK's development, so that might be a feature they've put in for Drupal 6. I'd say go look through their issue queue on drupal.org to see if there are any plans in that direction.