It is very useful when editing a 3D level to have a mouse navigation mode designed for traversal. For example, LMB press and drag to move the viewport camera forward, backward, strafe left, and strafe right. This mode should have a modifier for Elevation with strafe left, and strafe right (RMB press and drag). Another modifier for Orbit camera target/selection (MMB press and drag).
Is there anything currently existing that would expose similar functionality? The default setup is okay for small scenes and familiar due to its similarity to DCC apps like Blender, Maya, and Max. However, Large scale world editing needs something more efficient at both covering large distance and accurate in small spaces like interiors. DCC mouse navigation does not accomplish this very well.