I will continue to indulge my curiosity and maybe eventually figure this thing out.
There is a second publication on the subject from 2010 which I have not been able to track down:
Stephenson, R. (2010) Rethink Sedum adolphi. Newslett. Sedum Soc. No. 95: 23-24.
If anybody is able to locate a copy of this 2-page article on the interwebs, I would be curious to see it.