How to properly call an external WCF Service from SharePoint 2010?

Ended up keeping the SPSecurity.RunWithElevatedPrivileges section. Microsoft's SPChannelFactoryOperations at some point hit a NullReferenceException, most likely due to Claims required to be setup within the service even when not using it (SPServiceAuthenticationMode only has SPServiceAuthenticationMode.Claims as a member. The fact that CreateChannelActingAsLoggedOnUser() immediately throws an ArgumentException is a signal that the SPChannelFactoryOperations aren't meant to be used by non-Microsoft code.