Yes, I think I was aware of these other items you mention. Besides the complicated relationship double relationships between the Sturgills and Louderbacks, there are also multiple marriage ties between these families and the Wicklines and Vermillions. In my line, A.P. Louderback's and Mary Ellen Sturgill Louderback's daughter Rachel Elizabeth married Thomas Wickline and several other Louderbacks and Sturgills married Thomas' siblings. The Vermillion tie doesn't pertain to my own line, but its similar. The interesting thing is that this family is also tied to another group of Louderbacks in Kentucky, whose relationship to our group is unclear to me.
About the spelling of Louderback, I've seen many combination involving au, ou and ow in the first syllable, t or d at the end of that syllable and k or ch at the end of the name. However, I've also seen a German site that explained the entire name series as a corruption of Laudenback. I suspect the spelling used in the U.S. depended on several things, including whether the person spelling it was the family member or a bureaucrat filling out forms. Census are notoriously original in their spelling. On the Wickline side, Thomas' father was Collin Wickline. One census taker had his family listed as "Collin Weakland."