If someone pins me, I know it. The question is will I let my partner know? I think aikido is actually a great platform for applying pins without the discomfort of traditional pins, or the competition of a sport. First, we need to apply a combat filter to discourage non-martial responses that would damage our bodies. Second, we have to concede a successful pin without an obvious control mechanism in place. If we can do both of these things, we have a great environment in which to pins.
Here's the rub... for being a bunch of huggy-feely, harmony-restoring, ego-less, compassionate souls... we can be dishonest and passive-aggressive with the best of them. Also, some of us simply do not possess a combat filter to manage our responses. Bye the way, I've fought enough sankyos to know that I can be one of those passive-aggressive types. You need a good sempai that's willing to put a few on your nose to solve both problems...
I don't know if uke helping nage actually makes a difference here. But honesty does. I think you need an honest uke to feedback when you are in control of her body or what additional corrections are necessary to gain control. If she does that, then I do not think it is relevant whether she is "helping" you or fighting like the dickens to escape. I remember a seminar with Hooker sensei when we were doing tachi dori and Sensei has his uke on the ground and the sword is both addressing uke and applying this terrible nikyo. Uke is tapping and grunting and fighting and tapping and Sensei is just holding the sword. Finally, Sensei says, "let go of the sword." Uke let's go and the technique is over. Sensei says, "you're lying on the ground with my sword at your throat hurting your wrist, whadidya think you were gonna do down there?" Precious.
