I have long admired the roasting prowess of Peter G and CCC, and jumped at the chance to evaluate two of their newer offerings: 21st de Septiembre (a light roast Mexican SO) and the Espresso Rustico blend. In the past I have enjoyed several of their classic espresso blends, including Espresso Toscano, Espresso Aficionado (a lighter roast, excellent for straight shots), and Espresso La Forza (a darker roast, better with milk). I requested a bag of Toscano for comparison purposes, and Dan was kind enough to comply.

Living out on the edge of the civilized world, coffee takes a bit longer to arrive. Coupled with a busy work week, I did not begin sampling until last weekend, five days post roast. A Robur grinder, Spaziale S1, and Yama vac pot were used for testing.
I first dipped into the 21st Septiembre bag. My preliminary impressions (15-16g doses, 88-92C setting on the Spaz S1): mild, sweet, good body, loads of caramel (close enough to brown sugar), but far less chocolate than expected, with little if any obvious fruit flavors. A decent SO espresso, not terribly exciting; should make an outstanding base for an espresso blend. Holds up reasonably well to small quantities of milk (macchiatos).
I continued to sample this coffee over the next few days, both as espresso and vac pot brew. Oddly, I could not reproduce the overwhelming chocolate flavors described by Jim; at most, I got only slight hints of milk chocolate. Following advice from Jim and Chris, I tried updosing my espresso pours to 18g and pulling at 86C. The resulting brew was too sour, but some chocolate notes emerged with milk. At 88C the sourness became lemon citrus, with hints of candied fruit and marzipan in milk. Still very little chocolate. My first impressions held up well: this roast works as a SO espresso, but would be better suited for an espresso blend.
I also tried the 21st Septiembre as a brewed (vac pot) coffee. My first attempt produced a bland flavor profile, with decidedly bitter overtones. After this indication of overextraction, I ground coarser and reduced the brew time up north. My second attempt used a 1:14 ratio of coffee:water, coarser grind, 60sec brew time. Better, bitterness way down, nicely rounded, with a slight nuttiness. Overall, balanced but uninteresting; still no chocolate or fruit. It did not improve with milk.
So why no chocolate? One thing for sure: it's not an inability to taste chocolate flavors. I recently polished off a bag of Klatch Brazil Ipanema Dulce, a cocoa bomb if there ever was one. And I've been drinking some home roasted Yemen that has pronounced dark chocolate overtones.
Speculation: this roast peaks early and fades rapidly, with a very narrow window of interest. (Jim began sampling immediately, and noted the strong chocolate flavors on day two post roast.) So if you order this coffee, don't wait: start brewing it as soon as it arrives. It does not appear to age well.
Conclusion: IMHO this coffee is too bland for a SO specialty offering, and should be relegated to blend status.