This is an example of _**subject/verb inversion**_, not a case of _ellipsis_ as you said. We use this kind of inversion while _comparing subjects_ of the verb and not normally _objects_. We call it _inversion in comparatives_ as in > Paul is more interested in Maths than is Mary. > You play golf better than do I. So in this sentence, there is _no ellipsis_ of the subject. The subject is actually there after _is_ which is _the knowledge born of experience_. Actually a simpler way to write what is there in your example is > ... more measurable than the knowledge born of experience _is_