Just got an i2 shaft for my G407. Measured my joint at .841 and the i2 measured the same. (Nielsen's Billiards said the tag said .845 but they measured it to make sure and it was .841.) Fits perfect with no noticable shoulder, can't catch a nail on it at all.
Not saying they all are but that was just my recent experience. Hopefully some other owners will chime in and verify.