I got to throw each of these today thanks to the local Vibram tester. We also played a few holes together so I got to see them in action. My experience is pretty much on par with what the others have said.
The 420 is seriously OS, seemingly with no turn at all. On lower power throws or with any hyzer, it flies to the ground like a magnet, finishing at almost a 90 degree angle. For those of you who have been clamoring for a more OS Vibram disc, this is it in spades.
The 419 is the exact opposite, seriously US. I max out around 325', and don't have anything over speed 8 in my bag. And yet, I was able to turn this thing easier than my Underworlds: it turned for me and didn't come back on a low power throw with a slight hyzer release. Personally, I'm excited by the prospect of this thing: I feel like it could potentially be a great first distance driver for someone like myself. Once dialed in, the distance potential seems great for lower-power or finesse throwers. The tester I played with had some trouble dialing it at first, but managed to throw some awesomely straight tunnel shots once he knew how to finesse. I hope they don't alter this disc significantly in response to tester complaints: I know really US discs aren't very popular, especially with more advanced players, but for us newbies and noodle arms they can be a boon. Also worth keeping in mind that the 419s seem to be coming in lighter weights: the one I threw today was also 164.
One final thought: for wider-rimmed drives, these are quite comfortable in the hand. As unfamiliar with such drivers as I am, I felt fine holding and throwing these.
Definitely skips like you'd expect. The tester threw it flat and low on City Park hole 11 over the OB line, and it originally looked like it wasn't going to come back b/c it was too low to the ground. But that sucker had a good skip (on a shorter, lower power throw) up and in bounds. It was pretty sweet.
The 420 should be able to handle pretty much any wind.
Your review was awesome! Thanks for the excellent feedback. You answered all my questions and now these discs just need to be PDGA approved, named, and sent out to me! Can't wait to throw them.