I have not used slinsane, of course, but IME with Norvaline it is VERY synergistic with a lot of things(arginine & norvaline for instance). So I certainly wouldn't rule it out.
As far as any insuligenic responce, it does stimulate insulin secretion and increase 2-ketoglutarate generation in pancreatic beta cell mitochondria through activation of glutamate dehydrogenase and transamination with l-glutamate and l-glutamine, but thsat is at higher doses and l-leucine acts the same EXACT way with a much lower wallet effect. Personally, at lower doses, I have found any effects of Norvaline negligible at best and I have yet to find a supplement with a worthwhile amount of norvaline in it. Again, I haven't used said product, so I can't comment on that...it does sound interesting though.