I haven't personally and wouldn't use him on heifers. Saying that, I have a cousin that has used him on heifers & got along, but watches heifers extremely close & did pull the majority of the Pricsless calves out of heifers. He's no problem on mature cows.
I used him on heifers....ended up with 2 c-sections, and pulled the other ones! On top of that, nice front ends but absolutely nothing else, I wouldnt waste yer time using him on anything!