Thanks! I'll switch to there.
EDIT: Er, when I try, it tells me "Warning: this topic has not been posted in for at least 120 days. Unless you're sure you want to reply, please consider starting a new topic." So I guess it's better to use this new thread instead. (I'm kinda new to these forums, and I'm not sure of the etiquette.)
I don't have a good way to simulate this easily, but I've played perhaps a hundred solitaire setups, and I'm pretty sure Bishop/Chapel is the best opening. I've tried buying only one treasure before paring down to 5 cards, and I've tried buying 2 treasures before hitting the 5-card goal, and both seem good. (In each case, a first Province on turn 8 is common, with turn 9 also common, and occasional horrid misfires that don't line up for a painfully long time.) I'm pretty sure that buying a third treasure is slower, even if it's gold. And that second treasure might be suboptimal too; I'm just not sure. Each card you buy increases the odds that it will take several turns longer to get down to 5 cards; it's usually better to "trade up" to gold once you have control. I also tried buying nothing between turn 2 and when I get a 5-card hand, but that's clearly slower.
To be more specific, if you have a 5-card deck of Bishop, Chapel, and Copper x 3, it takes 4 more turns to get a Province. If your 5-card deck has two Silvers instead of Coppers, it just takes 2 more turns to get a Province. That's worth it. But an additional Gold, even if you can buy it, only gains you a turn once you get in set up, while making it much more likely to take many more turns to get to that 5-card goal.
As for attacks, it seems to me that any time an opponent curses me it sets me back a turn. On my next turn, I have to lose a card by bishoping and declining to buy in order to get back in the swing of things. (I could put it off a turn, or two if I'm lucky, but I risk not drawing my Bishop. If that happens, I have to skip the turn completely, or give up on the golden deck strategy.) I doubt the strategy can be sustained at all in a tableau that includes cursing. And Embassy can hurt a little too, though it only sets you back a single turn (per buy).
Militia (or Goons or Margrave or Ghost Ship) also sets you back a turn each time you're militiaed, though you can still Bishop a Silver for 2 VP and use the Gold to buy it back, so it's not a totally lost turn. 2 VP per turn is pretty slow though. I don't know if a Militia barrage could effectively defeat a golden deck strategy or not. And Embargo on Provinces is absolutely poison, as Voltgloss pointed out below. Deck attacks like Pirate Ship, Saboteur, Oracle, Fortune Teller, etc., have no effect at all (though note that Noble Brigand is just as damaging to this deck as Witch is). And Bureaucrat and Cutpurse might slow you down a tad, or perhaps not at all.
If someone does effective simulate different strategies for setting up the golden deck, I'd love to hear the results. For instance, I'd still like to know at what point it's better to abandon the plan and try a more traditional Bishop strategy.