If you look up the phase chart for steels at various temps, even 1400F isn't nearly as bad as one might think. And that assumes that the r-value of the wrap is ideal, loosing zero heat to the outside. Stainless doesn't absorb heat as quickly as regular steel (~1/2), and you can't heat a container beyond the internal medium, at least not with the minimal friction air creates. The main problem is the heat causing it to loose it's ability to resist corrosion, but with turbo engines, you have practically zero reactive gas (mainly oxygen) left in the exhaust.
I've ran 2 manifolds using mild steel, cast steel, and cast iron with lots of heat wrap, and haven't had any cracking issues. And this is from me doing "sloppy" mig welds by not pre-heating the cast metals. The fact is that most people with such expensive manifolds won't drive their cars often enough to worry about heat. I'd guess that Corkey Bell was refering to all-out racing applications. Honestly though, Honda guys don't daily drive their 400whp vehicles as often as Evo owners.
Back on topic, manifold looks tits. You are definately the Tony1 of RHMT.