" I have almost 300 000 users on my old online store and now i switched to Magento. I wouldnt try to do that on my own, it would go on forever. Maybe this will help: http://cartmigration.com/category/cart-migration-tools/magento-migration. They promise to do everything automatically and in a very short time. Can i trust them?"
I read similar questions, who has the same questions? :)