The plugin works exactly like we had hoped. It took a little work to get our settings correct for the intended benefit but we finally got everything working correctly. The plugin is very stable. We have contacted support a few times and they are very responsive and helpful. I highly recommend it.
Shops that sell varieties (multiple sizes, etc.) must use WooCommerce Size chart for their products. It makes descriptions more appealing and clear.
Offering free samples for WooCommerce require a comprehensive product sampling strategy. Read to know more about the science of free samples.