Has anyone successfully imported customers, orders, ship to, and bill to addresses using anything other than a custom module? If there a recipe for the process?
There's also Migrate Module ; but your question is vague regarding the source you are migrating from. This module supports different sources to migrate from
Depending on what you need, but I would go with Migrate module. You've got a commerce migrate module and if you're coming from Ubercart, you have commerce migrate ubercart already baked in - also useful if you want to look for examples. You're going to need to build your own migrate classes, check the getting started with migrate guide in drupal.org.