For Vintage I don't think the London mulligan is incompatible with the format, but the current restricted list is certainly not optimized for London.
Something that occurred to me after I posted is that I assigned a certain negative value to "influences deck design" because it was treated as a negative in the original Stoddard article, but that's not really fair--any mulligan rule would influence deck design, including the presence or absence of a mulligan in the first place, and we don't need to anchor our reaction to London to the idea that the deckbuilding trends encouraged by Vancouver are ideal. It occurs to me that there might be some other neat possibilities opened up as well--if mulligans can be an intentional part of your gameplan in combo, can they be part of your gameplan in aggro? Midrange? Could this be Sphinx of Foresight's time to shine at last? So I guess I'm coming around after all, provided that we can also get the appropriate DCI action to go along with it (which unfortunately isn't a given).
I'm not on Twitter so I'll chime in here. In the abstract I like the London mulligan a lot. It feels much better especially when you get two bad openers in a row, and the experience of using it really won me over. Taking the same decks from a few weeks ago and applying the new mulligan rule to them just makes games more pleasant, on average.
Which is why I'm so glad that you were able to demonstrate what happens when people don't play the decks from a few weeks ago. The key point in the Sam Stoddard article about this mulligan rule was that it influenced deck design, and wow is that ever borne out by your Outcome list's evolution. I think that's about as clear an illustration as possible that the London rule is ill-suited for Vintage, if the goal is simply to reduce the frequency of mana-screw without substantially impacting deck design along the way.
Eh, I like this card. I've been playing Disenchant in UGW Xerox and it's been perfectly cromulent, even if I wouldn't defend it as absolutely optimal. Occasionally telling a Snapcaster Mage to go pound sand is a nice bonus. Nature's Claim is probably still better but I'll probably play this as a maindeck fun-of anyway.
That's what I'm wondering about. By my count there are three PWs that see a lot of play right now, and a couple more that see fringe/sideboard play. There are, what, seven in WAR that seem to have potential? Plus Kaya which is probably poised to see an uptick in play. There's not room for even close to all of them to show up in established decks, but I'm really curious about a possible superfriends deck that might emerge.
That was exactly my reaction to it. I don't think this is likely to find a home in the next 6-12 months, but five years from now somebody is going to be lauded for remembering that this card exists and breaking some troublesome matchup wide open with it.