We used Dark Horse his first year on a couple cows. Do not use him on heifers. We got 2 bulls and they were plenty big. Turned out decent, but definitely not a heifer bull. Maybe try BC Classic at Select Sires for the heifers. Good luck...
I would not use Darkhorse on heifers. If you like the SAV bloodlines a proven bull would be SAV Bismarck that would be calving ease. His calves are also very marketable also.