This is a hard (and good) question. I probably practise in a manner similar to the folk Jeff trained with (at least from the description). Even in my home dojo though, there is a wide range of technique depending on the partner...male or female, newbie or old hand, a person who likes to be thrown hard, or someone who is nursing an injury or just doesn't prefer the harder throws (sometimes just for that moment, sometimes not at all).
The male female dichotomy isn't meant to be sexist...its just that unless I know a woman likes to train recieving really hard throws, I have a great hesitancy about appearing to bully them. I guess that really applies to anyone, not just women. And I definately know women that don't have a problem with hard throws, and who can and do indeed throw hard themselves. Some of them harder than I can throw.
For me, the line for "violence" in the dojo is whether or not I abrogate uke's trust. This leaves a large range of physicallity in my practise.
If uke's level of trust as a beginner means "please don't cause me any pain", then it is my job to help them participate as much as they can in aikido without pain...they are a beginner, and special care must be taken. Hopefully, they will understand that as time goes on (at least in the practise where I train) a certain amount of pain is often a part of training. With said beginner, if they tap, I do not increase or maintain the control or pin, rather, I release it a bit.
With someone else who is experienced, say a shodan, the level of trust is much greater. This particular shodan might train very hard, but perhaps they are of slight build, and much lighter than I am. I can really take their balance, and really throw or pin them, but I won't throw them in such a manner that pushes them too much in the level of their ukemi unless they want me to. I will concentrate my technique on proper movement, taking their balance, good form...but not power, and only moderate speed. Again, the critical issue is maintaining that person's trust **whatever that takes**.
Another person might have been training the same amount of time I have, going to Daito ryu seminars with me, training after hours in shotokan, and regularly engaging with me in "rough" practise. Baring any injuries, we might train in a manner which would cause some people to go pale just watching. But there should be a minimum of physical injury...and no injuries that would keep *them* out of practise. Here I might use quite a lot of speed and power as well as technique, and they would do the same to me. If they are applying a control, they might do it hard enough to disrupt my breathing...my tapping would not mean to stop or lessen the technique, it would simply be a way for them to gauge the strength of the control. They might very well increase the control, and my tapping harder would give them a way to gauge the increase. If it was too much, I might say matte...or stop. Again, trust is the barometer. No trust broken...then the application is appropriate. Trust once broken is extremely hard to regain...sometimes it never is. Like technique, you often get only one chance.
As far as an "real" attacker...who knows. I will strive for complete and absolute control...that way, I might safely determine whether or not I can show mercy. In my opinion, without such control there can be no true mercy in a real situation.
As far as striking on pins, Ueshiba did it. Look at both Budo Renshu and Budo. Daito ryu does it. Yoshinkan does it. It is standard practise and accepted in many variations of aikido. If some prefer not to do that, no problem. They should follow the traditions of their specific teachers.