Retained probably 90% of my hair after 6 high dose chemo (taxotere, carboplatin and epirubicin) see picture below.
Kept cap held tight to my scalp with my hands throughout (long days but worth it to keep my hair and have managed to keep my diagnosis private because I didn't lose hair)
Hair continued to grow throughout (hence the roots, didn't have hair cut or coloured during chemo)
Took strong painkillers half an hour before as very painful, and took hot water bottles and blankets.
First 20 minutes agonising for me, but again, I felt the pain was worth it, and after 20 mins you are numb. Short term pain for long term benefit, that's how I got through it. [[{"fid":"106731","view_mode":"default","fields":{},"type":"media","field_deltas":{"1":{}},"attributes":{"class":"media-element file-default","data-delta":"1"}}]]
Good luck if you're giving the cold cap a go. I would definately say it's worth it.