Short answer is I have it for legacy and didnt want to criss cross, but it is a consideration to be sure. I started vintage with Dredge and I'm not in love with how autopilot some of the matches are, and I don't like how it can literally drop to a tier 3 deck depending on how people decide to sideboard in the meta. Splash hate for Survival and possible Phoenix builds literally drop dredge percentages more than I like.
As much as the London Mulligan is going to give it a percent or 2 boost to hit bazaar every game, I actually suspect it will help other decks hate it out even more. It not only helps decks find leyline and Relic/cage faster, the reduced hand size can actually be a huge boon to a deck like Blood Moon who can get hellbent easier for ensnaring bridge.