Before I start this post, here is an interview with Telegraph's Brian Thompson on the Beer Samizadt blog. Since I read this post I've had made it a point to try Obscura Petit (which I had seen on tap at Pizza Port Ocean Beach) and Obscura Arborea (which I had purchased a few months ago). Petit is a tart, sour beer that weighed in around 4.5% abv. What a delicious beer. It's a sour without sweetness. A subtle bitterness appears in the finish and complements the sour. Petit is my favorite type of sour, moderate alcohol, lively, funky sourness, and limited sweetness.
I've never been bitten by the barrel aged bug, and Arborea is oaky from its time spent in barrels. Its oak overshadowed the yeast and related sourness. I liked this beer and would buy it again, I think I was just expecting more from it. I've had several Oude Bruins, but am no expert. I need to find a style benchmark so I can properly gauge sour beers.