Zinfandel v. Syrah (v. Primitivo) Part 2

So back to that question: what differentiates Zinfandel from Syrah in a blind tasting? This came up from a blind comparative tasting in the last WSET class. My friend turned to me after the wines were revealed and said he could have sworn it was a Syrah that we just tasted. Well, true. The wine was balanced and didn't taste overly hot, but it had lots of spice and darker fruit. It was full bodied and structured. There was no obvious markers to trigger a reflex...we ran into what drXeno called "one of the most difficult cases of guessing a blinded wine’s varietal…New World Syrah/Shiraz vs. Zinfandel."


In the Wine Bible, Karen McNiel describes Zinfandel as a "mouth-filling dry red wine crammed with jammy blackberry, boysenberry, and plummy fruit." Syrah on the other hand has flavors that "... lean towards leather, damp earth, wild blackberries, smoke, roasted meats, and especially pepper and spice." She goes on to say that in the New world this can lean more towards the "... softer, thicker, more syrupy boysenberry-spice character." The masking/homogenizing effect of oak can cause further confusion between the two.

I've thought of a few potential markers to keep in mind. My first though was that white pepper and strong cedar notes would be giveaways for Syrah, but after a little more thinking and research, I've come up with these: 1) Zinfandels tend to be higher in alcohol than Old World Syrah, though this may not help with New World Syrahs. 2) Zinfandel displays more red fruit than Syrah. 3) Zinfandel lacks strong tannin. 4) Brettanomyces would more liekly be found in Syrah than Zin. Given that Brett. is viewed strictly as a flaw in the new world, it would be hard to imagine a barn-yardy Zin, but is potentially beneficial to pedigreed Rhones.

Any thoughts on the matter? What are your experiences with these two varieties?