Here’s a migration class I’ve been working on to import 8200 products. The biggest feature of this code is that it will automatically create a single product display node that groups all products who share the same “grouping identifier.” So, in my CSV import file I have a “grouping_identifier” column. If a product is available in ten colors, and they all share the same grouping identifier, a single product display will be created and each of these products will be referenced in it. This will result in a product on the frontend that allows ten different color choices. I don’t have the time right now to explain anything more… please leave a comment if you have a question.