Not opening Chapel and trying to top deck it with Armory drastically increases the chances that Chapel misses the first shuffle. You NEED Armory on Turn 3 for the newly gained Chapel to make the second shuffle. Armory on Turn 4 just puts Chapel in your shuffle missing next hand.
Considering you want an Armory at all, your kingdom has enough sweet $4 or less cards that you do not immediately need that Silver, so this is a no brainer for me; open Chapel!
I think so too. I was just presented with an interesting board on the first game of the Dominion Championship S16, where Armory could pick up a ton of Moats and Walled Villages, which aren't so great in the beginning. I was wondering then whether to open Silver/Armory to hopefully spike $5 and get a Lab, or just begin with trashing and not quite hit $5. Of course, you could just gain Silver with Armory and then hit $5 anyways.
I think that's the correct play, gaining Silver with Armory when you have reasonable confidence you'll hit 5 and not hit Chapel next turn, and gaining Walled Village if you won't. You open Chapel / Armory and then the following situations play out:
1. Chapel in Turn 3: Trash everything, Armory in Turn 4: Gain a Silver if there are Coppers left in your remaining 2 cards.
2. Armory in Turn 3: Gain Walled Village, since you can't risk falling behind in the Chapel race with a wasted Silver gain. Chapel is either Turn 4 or 5.
3. Collision in Turn 3/4: Trash 3 cards and sigh.
I feel these scenarios play out better and are more likely to be helpful than the Silver open scenarios. Trash first, but $5s every turn later, or get lucky and spike one early $5 while slowing down both your trashing and gaining on average? Not tough.