So I printed the first 9 of this set out and we played a game tonight with Astrolabe, Canal, Barge, Landfall, and Harbinger (along with Shantytown, Sea Hag, Trade Route, Island, and Horse Traders.
Barge was a great opener for trashing, and Trade Route became useful with all the alt-VP cards once they were bought.
But the far and away most-overpowered-card-on-the-board was... Harbinger! One player got one early, followed by another 3 of them and a couple golds, in a deck trimmed by barge, and it was a runaway victory.
Harbinger is much better than Laboratory for the following reasons:
1) You generally choose between 3 cards and 2 cards, whichever is better for you, based on looking at the cards already in your hand (compared to Lab giving you just 2 cards, without a choice, sight unseen).
2) You can guarantee that you will get the "one card you need" from the next 5 cards, which is often crucial.
3) Since you draw a total of 5 cards, it helps with cycling which helps in building an engine.
4) Once you hit a "critical density" of Harbingers (~ one Harbinger in every 4 cards in your deck), you end up with starting hands of two Harbingers, where on the first Harbinger, you can just take the pile with more cards in it (guaranteeing you getting 3+ cards), followed by playing your other Harbinger, and they start feeling like always-activated Menageries.
At the end of the game, we unanimously agreed that Harbinger was an interesting card, but that it should cost 6.
Otherwise, the cards and the game were very interesting. Well done, card designers!