I do a lot of comparing 3DCart and Volusion. I process orders in both carts everyday. One area that I think Volusion lags behind 3dCart is their email followup system. Both carts do a good job soliciting product review post-purchase but Volusion's Abandoned Cart Followup email system leave a lot to be desired. For one thing, it isn't automated (this should have been a no-brainer) and customizing the email isn't easy (for instance the email subject line can't be changed).