I found this 7 minute clip of Christian Tissier Sensei giving a very interesting ikkyo lesson. WOW!! I hope. Not sure I've done it correct with the link, but search in youtube.com for Christian Tissier Ikkyo
I suppose I tend to be a rather nice nage, but even if I'm not (within reason), uke can still roll out of the ikkyo - providing he initiates his roll early enough. I haven't actually tried to be ultra-violent as I think it could be quite dangerous to violently "catch" his head against the mat as he is actually trying to roll - neckbreak fear !!!
I will ask Sensei about this and humbly beg for an hour of ikkyo-wisdom specifically around my little "ikkyo problem". I
All the best