No badge-owner here to attest to the inner sanctum workings of the 10 but I read with great interest the article about the FTU and the reasons for picking the 10.
Note: did not recently read this...still have my copy with that article from back in the day and remember Mr. Hall and his partner saying something to the effect "make the first digit a 4" as far as caliber selection. It`s kind of been a guiding principle for me when selecting a handgun. I bought a 1006 in 93? upon hearing that it was no longer the chosen for the FBI and although I don`t shoot it that much any more it`s not for sale. I do follow the first digit advice to this day though when I`m out and about.