Thanks for this. How can I modify this to ensure category level visibility of the 'Add to cart' button? Here's the attempt:

1. The catalog category is split into 2 heirarchies at the highest level.

2. One category and its sub-categories display items for sale, and have a sale price etc., so the add to cart capability is required.

3. The other category and its sub-categories are for 3rd party affiliate links, so while the items are shown with prices, I'd like to remove the 'add to cart' button as the product description will have an eternal link.

Thanks
S