I currently have a WordPress site that I built that uses posts as products for over 5,000 products at rsci.com. The products are posts with a link that brings the visitor to a remote shopping cart. Is YAK practical for large catalogs and could I do a simple export to xml of current posts then import them back as YAK products? Thanks!
Whoops, missed this, sorry.
To be honest, it's not something I've looked at. YAK uses posts as products -- a post maps to a row in the wp_posts table, so there's not a lot of overhead required. Managing that number of products might not be that straightforward though.
In terms of export+import, I notice the wordpress-importer plugin doesn't allow you to override the category - so it's not going to be that straightforward.
You could try TaxNOW for WP e-Commerce. It's a new plugin from Evolving Office. It connects you with Avalara who calcualtes sales tax automatically.
How exactly does that relate at all to the poster's original question?