I think in the general case (ignoring the rest of the kingdom), Urchin / Swindler is better. This is largely because of the relatively small chance of significantly slowing down the opponent by trashing a power card combined with the value of a terminal Silver in the early game.
However, in this kingdom, you don't exactly have power $5 or $6 cards to pick up. You're going to probably want to bulk up on 3 and 4 cost cards, so the drawback of Urchin / Urchin leading to weak second shuffle buying power... just isn't much of a drawback, really. You can still pick up a Caravan or two, maybe a third Urchin if you hit $3. I'd rather get Mercenary faster.
The Procession buy by Adam is really what I think was critical here though. As a mechanism to gain Caravan quickly, while dispatching with now less useful $3 cost cards, it's hard to beat. Plus it's a village, sort of...