We moved from Channel Advisor to SureDone about 6 months ago and we were very nervous about adjusting and migrating. My fears were proven to be just that.. fears on my part. They did a deep dive on the special needs we had and made adjustments for us at a reasonable cost. They have been right there for us and EXTREMELY responsive to my questions and issues.
Customer service team is right there for me and I found that the back and forth with Channel Advisor on issues was non-existent with SureDone.
With the changes they made for us we have doubled our business on ebay simply because the custom work we did allowed us to make technology changes on our side allowed us to offer more product which = more sales!