Sellbery is not equipped to transfer items from M2ePro to their system. Their system is convoluted and slow. They are not flexible in allowing you to have multiple variation items on eBay. Their order system doesn't work with Signifyd. Every small change takes an insane amount of time. Most importantly they do not stand behind their word. For any customizations you have to pay up front and regardless of whether they tell you you will receive a refund if it doesn't work out they will drag it out until you can no longer take any action and will not refund you. For anyone with a large catalog stay far FAR away from Sellbery.