I would think that grabbing mane to mount would be more painful than grabbing the saddle to mount. How would you like it if somebody grabbed your hair to help get themselves up.
Either way, I try to mount using a tall mounting block so that I can just slide over, but that is because I have had several injuries to my left leg and don't have the strength to do it any other way. If I have to mount from something lower such as on a trail ride I have somebody hold my off side stirrup while I struggle up. :p
RH Queen O Anywhere "Sydney"
2009 Sugarbush draft