I've been looking at the Gold Demo and so far am very impressed.
One 'feature' that seems to be missing, though, is the ability to re-enact the war with the exact same choices the participants made.
Why would one want to do this?
Two reasons.
First, if you want to find out if you could have won the battle of the Marne as the Germans (or, conversely, stopped the Germans at the Marne), it really doesn't do you any good if your opponent makes anything other than the exact same choices that they did historically. It doesn't do you any good if you follow the von Schlieffen plan to the letter, only to find that the French aren't using Plan XVII. That's fine for free-form play, but it doesn't address the question of whether you could have done any better than your historical counterparts (which is why you play historical as opposed to fantasy wargames). This is what changing history is really all about -- you have to be sure that what you're changing actually is history.
Second, if you can play an opponent who will make exactly all the historical choices, and you make the historical choices as well, most of the time you should get an historical result. There are a couple of reasons for wanting to have the ability to play in historical lockstep on both sides. One is to be sure that the model works -- if the final outcome doesn't look historical most of the time something needs to be tinkered with. But the other, assuming that the model is correct, is really educational -- seeing both sides behave as they actually did is very illuminating when you're trying to understand what happened and why.
So I guess what I'm asking for is a mirror set of scenarios (or maybe a toggle switch) that ensures that the other side in all of the different scenarios acts exactly as their historical counterparts did.