I am currently maintaining two child portals on the same DNN installation, each carrying the same products. To do so, I first tried to do data synchronization, with the products in each child portal carrying the same product number. To be honest, this was not working very well for me though I no longer remember exactly why. Since I do not maintain inventory for my stores, I ended up turning off synchronization and, instead, did an XML export from one store with products and then an import into the other store. I don't have a lot of change in the "inventory" so when I add something, I do it manually to each portal at this point.

The thing that I recall about the synchronization method (again, I no longer use that method), is that certain data fields but not all are synchronized. I think the product description is synchronized, if I recall, but the title is not though I only briefly tried this method before concluding I didn't really need it for my particular solution.

Anyway, the point is that it is possible to have one code base for products using synchronization. However, I spent so little time with that technique that Susanne or someone more knowledgeable about it would have to respond on the more technical aspects.

Hope this helps.