I am not convinced there was an implied agreement to preserve secondary market prices outside of the Reserved List, at least for cards which are Modern legal. As you mention in the article, one of Wizards' stated reasons for establishing the Modern format was to have a non-rotating format that wouldn't present a significant price barrier to entry. I think it's pretty clear that this constitutes an announcement by Wizards that there is no promise of value retention in Modern-legal cards, that what has been true for cards before Modern is no longer true. In this case, there isn't merely an omission of a verbal/written contract; there is a stated rejection of such a contract. Wizards essentially said, with the Modern format, "We are providing these cards but you are hereafter warned that they are open to reprint at any time."
That being said, I can't help but wonder if there is a point where enough time has gone by, much like a statute of limitations, where that original statement becomes invalid. Even though Wizards appeared to intend this to be the rule for Modern, they have not really lived up to that. Personally, I consider the low price barrier concept an essential point of having the format. However, we now live in a time when certain cards in Modern cost more than the expensive cards did in Legacy at the time when Modern was created.
I honestly think Wizards should consider banning cards from Modern purely based on their price having risen too high. Either that or do a real reprint of these cards (Modern Masters doesn't count because the price per pack still presents a significant price barrier).
4x Fabled Hero
4x Phalanx Leader
4x Hero of Iroas
4x Soldier of the Pantheon
4x Favored Hoplite
4x Hopeful Eidolon
2x Gods Willing
4x Dauntless Onslaught
2x Spear of Heliod
Some things I have experimented with that didn't work well:
Brimaz: He doesn't interact at all with the Heroic/Bestow component of the deck, and competes with Fabled Hero and Eidolon of Countless Battles in the curve. I found in testing I was almost always ending the game with him still in my hand.
Elspeth: By the time you cast this, the game should be over.
Phalanx Formation: As an alternative to Dauntless Onslaught. The damage potential is pretty high, but it is severely weakened if Fabled Hero is in play. Also, I don't think it's worthwhile to use it only on one creature, and I don't want to need 5 mana for anything in this deck.
Nyxborn Shieldmate: This is okay. I was divided on choosing between this and Hopeful Eidolon. You could go either way.
The deck has no maindeck removal, mainly because it's difficult to test that in solitaire (I've mainly been using tappedout.net's browser-based playtester since I can do that from my work computer). I'm not really sure if I want any. This can be explosively fast, and any removal spells will act against that if they are drawn. But I would also not be surprised if it ends up being worthwhile to play a couple Reprisal, probably at the expense of 2 Hopeful Eidolons.
There are basically two ideal routes to a turn 4 win:
Turn 1: Soldier of the Pantheon
Turn 2: Hero of Iroas (attack for 2)
Turn 3: Bestow Eidolon of Countless Battles on Hero of Iroas (attack for 8)
Turn 4: Attack using either Dauntless Onslaught or playing a couple cheap creatures/spells targeting Hero to get extra 2 damage to win.
Turn 1: Soldier of the Pantheon
Turn 2: Phalanx Leader (attack for 2)
Turn 3: Fabled Hero (attack for 3)
Turn 4: Attack, play Dauntless Onslaught targeting Phalanx Leader and Fabled Hero (for 19 damage)
The other stuff in the deck basically all support stuff for when you can't get these plays.
I don't think the deck is quite Tier 1 level yet (it can suffer terribly from having only 2 land or too many land, both of which happen often enough), but the results are pretty impressive considering it is Theros block only.
Recently I've been playing 4 Aetherize in the sideboard, and I bring them in against this deck (and others). It's extremely effective against the Pack Rat strategy. And with 8 board wipes in the deck, it will be hard for your opponent to get all of them out of your hand by discard.
Beta Black Lotus: Only 3300 printed. Only usable in the least-played format, and only as a 1-of.
Typical eBay listing: http://www.ebay.com/itm/Magic-the-Gathering-Beta-Black-Lotus-Vintage-MTG-Power-9-/111323793838
foil FoW: people are estimating under 1000 sent out. Useable in Legacy as a 4-of (which most decks have).
Summer Hurricane: unknown number, probably less than 100 in existence. Has virtually zero play value.
eBay: http://www.ebay.com/itm/MTG-Summer-Magic-Edgar-BLUE-HURRICANE-x1-Misprint-BGS-8-5-NM-MINT-/121268776707
So yeah, probably somewhere in between, but keep in mind that the Summer Hurricane's value is 100% due to scarcity, while FoW also has top-level play value. I'm not sure that difference in play value is enough to compensate for the scarcity difference, but it should have some kind of effect to push FoW higher than it would be as a 1000-of useless card.
If money is a concern, you should already be trading away any cards that will lose value after rotation. There is actually a fair amount of stuff from RTR and M14 that sees play in Modern, so it's less of an issue than it might be in other block rotations. However, some valuable cards that aren't seeing play outside of Standard include things like Boros Reckoner and Blood Baron. Probably best to trade these away if you still can find people who want them. I stop playing Standard June 1st and work hard to cycle all old block stuff for new block stuff. Then I play Standard again in the fall when the new block starts. But I wouldn't worry too much about what deck you are going to play then, since everything could change with M15 and the new block. That being said, if you have a Theros block deck that can hold its own against current Standard, it's not a bad place to start.
Also, in light of the fact that extra Mox Opals function the same as Lotus Petal (which is restricted), why hasn't Mox Opal been restricted in Vintage yet?
Mostly this. But against aggro, you should "waste" your Syncopates on Dissolves on any creature you can on turn 2 & 3.
But you should also be playing some number of cheap removal, typically 1-2 of some mix of Doom Blade, Ultimate Price, or Devour Flesh, along with a couple Hero's Downfall. These are weak against aggro (you want much better than 1-for-1 trade against aggro), but aggro isn't everything and these are good against midrange decks.
For sideboard, I've had really good luck recently boarding in 4 Aetherize to function as Verdict #5-8. In certain circumstances it is even worth it to replace the Verdicts with those after sideboard, particularly if they are playing a deck reliant on producing token creatures (white aggro or Pack Rat). Being able to board wipe for 4 CMC during their own turn is such a huge tempo swing and unlike verdict it does not commit you to giving up the option to counter spells during the their own turns.
EDIT: Oh yeah, and there is a subforum under Standard -> Competitive -> Proven for this deck, and you can get a lot more high-quality recommendations there.
Well, it's all a moot issue now anyway.
http://tappedout.net/mtg-decks/white-aggro-next-standard-rotation/