We had 4 of them, all out of mature cows, all unassisited with plenty of vigor. The 3 heifers were 96, 76, and 80. The bull was 118 (out of a Godfather cow that usually puts some birth weight on her calves). I wouldn't use him on a 1st calf heifer, but wouldn't be afraid to use him on 2nd calvers. The gestation lengths were normal +1, -14, -3, +2 days (using 283 days).
I really liked them. Sold them all for show calves. They get better and better the older they get. The picture in my avatar is a Bojo X Kadabra we raised.
Hope this helps.