not very effective with big strong attacker.
When done at speed with the intent to dislocate the elbow the angle of the arm is irrelevant, or so I've found. When done slowly the execution must be perfect otherwise the arm does need a bit of elevation towards the vertical but I prefer not to commit so assertively the body weight in such a manner... there may be 'friends' about that need attention precluded by excessive dependence of the body weight. But then, I'm big and moderately strong as well as fairly good looking.
I have no experience in the Tomiki system but have been shown this technique by Yoshinkai, Iwama and 'standard' Aikikai instructors.The form shown in the photos do not match exactly the positioning of nages arms that I'm familiar with but fairly close.