The best nikkyo to me was painless. There was no pain, but I fell down anyway. Think about that for a moment.
Joe Thambu Sensei of Shudokan (Yoshinkan Aikido), said during a seminar that it's (since this is Yoshinkan I'll use the Yoshinkan term) 1st control (ikkajo), 2nd (nikkajo) control, 3rd control (sankajo)... etc... not 1st pain, 2nd pain, 3rd pain... When I was his uke, I felt no pain what-so-ever.
The best techniques I've ever experienced done to me were painless but still have control. I'm still learning on how to implement this. Pain is not necessary, but pain do sometimes happen, but don't let pain be the goal of techniques execution. It is about control.