I have tried cedcommerce for about 2 months and it is a lot of work to use. There is no automatic matching based on your existing eBay listings and you have to set up a bunch of different “profiles” and “templates” to match your Shopify listings to the existing eBay listings and got several inventory and price sync issues that take support several weeks to respond. These are issues that occur silently so you won’t see any errors in the sync, but you would notice when manually reviewing discrepancies. It also looks like the old eBay app left some custom attributes (eg. “sku”) on listings that can’t be changed.
I think its about time we make a new platform