I'm no geneticist, but isn't this "structural" number still valuable for other purposes? Also isn't the 6pp also "structural" so modulo my previous complaints we're comparing like measurements?
Yes it can help you work out how related two species are to each other, but as a means of knowing what an individual gene does in each species it can be highly misleading. Ask any pharmaceutical researcher how much the concept that sharing a gene means sharing a function can lead you astray.