I just had CubeCart Support upgrade my store from Version 4 to the latest Version 6. They did a fantastic job! My store has over 4,000 products and over 8,000 customers. All the data is in perfect condition after the upgrade. The upgrade was done quickly and professionally. I couldn't be happier with their service. If you are the least bit nervous about upgrading, purchase a support plan and let the experts do it. You'll be glad you did!