Hikermor, if that question is for me, the answer is I don't know. Regarding serrations on the spine, there's another advantage that I enjoy. The serrations on the spine serve as a scraper for a ferro rod. If my only fire starting gear includes a ferro rod and a knife with serrations on the spine, I still don't have to mess up my main edge. Further, the serrations on the Kershaw Roughneck can generate a thick shower of sparks, way more sparks than any dedicated scraper I have. The comparison is not even fair. The same is probably true for other serrated knives.
If you're reading this, it's too late.