Jumping in a bit late here...
I've been in dojo that practice rokkyo, and other dojo which do not.
The wakigatame that Chuck mentions is like rokkyo, but the way I've seen it done more frequently is as a ground pin (rather than standing). Often, it's done during tanto dori.
As far as yonkyo goes, my limited experience with the technique has been that I've had to work with it as a balance-breaking technique rather than a pain-compliance one. Sometimes, I just can't get the pressure point. Also, as far as I'm concerned, I would rather train to control than train to cause pain...