While impatiently waiting for a reply I did manage to uncover this document detailing a huge amount of what people want to know about gas valves. So, I thought I'd share.
The important detail that is relevant to my question is that it implies that most gas valves are designed to take a range of inlet pressure (11-14" WC) and adjusts it to about 10" WC on outlet. I can only assume that it does so with the integral regulator. Also it does say that valves will not fail or lock up if used with excessive pressure, it will merely regulate poorly.
So far, I'm concluding that you could probably design a high pressure system and then use a needle valve to step down the pressure leading into a gas valve since you don't need an exact pressure for them to function correctly. Though I guess it's only a tiny price advantage over just using a single stage 11"WC regulator.