Ford kindly points out that, in fixing atmospheric nitrogen, as in so much else, the devil is in the details.
High %N can be good, if you want fast release, but did you notice that 220880 produced less than 1/3 the biomass of 206492? If that’s what actually happens in the field, total N contribution would be much greater for 206492. (Similarly, high % protein isn’t enough, by itself, to convince me that some new crop species is worth developing. How much protein does it produce per hectare?)
Maybe Luigi will share his finder’s fee?