I'm going to order it and will be curious to see what it turns up.
Question for you. How much value does it add to recruit known R2 cousins for the project? Up till now my impression has been that my brothers and male R2 cousins testing was redundant as I was expecting that we just repeat similar results. (My brother recently tested at FTDNA and we only did the minimum Y test as we expected him to test the same and didn't see anything to be gained from more than the Y-12.) With this new Jewish R-M124 do we gain any additional data by getting more know cousins to test? It turns out that I have numerous paternal line 3rd cousins which would all test R2.
Terrific. I will put in a Big Y order for my cousin's kit this week.
It doesn't do much good to do more Y-DNA STR tests on your close cousins, because as you say, they will be redundant and most likely identical to you. The best thing to test for cousins, in my opinion, is Family Finder, as you may be able to isolate specific places on the chromosomes that are linked to some identifiable common ancestors in your family tree. This is not a perfect science either, but testing FF for cousins at $99 is a better way to spend money if you want to find more unknown relatives. As far the new Jewish R-M124 project goes, you can just be a surrogate for all your third cousins, because any common Y-DNA ancestors we find for you will be theirs too (assuming they are on direct paternal lines).
I tested my cousin for Geno 2.0 and Y-DNA because I'm not a direct paternal descendant on the family's R2 line, so I needed to find a cousin who was. He's now my surrogate for the Jewish R-M124 project because I'm not an R2. We are setting up the project to help with the same question you asked that might be asked by new FTDNA testers of Y-DNA, such as "How come I came out as an R2 when I have Ashkenazi Eastern European ancestry? How did my line show up in Latvia (or Ukraine, or Lithuania, or Belarus) when most R2 is from Asia?"