Isonics says SoI and Si-28 are synergistic.
More in this link (from mas) isonics.com
They report about AMD looking at SI-28 in a joint-program, acknowledging "a proper balance between performance and cost" has not been found yet. (Coded as usual: Isonics expects the "..." will be found).
Interestingly, they dont list AMD in subsequent market predictions as an important user of SoI. So it appears AMD folded it after (or even without) trying. For good, I would not want too much ressources spent on looking out for a panacea.
SI-28 is not. Neither is SoI, btw. ;)