Just wondering what kind of extension the upper dans have and what kind of feeling it is to be REALLY thrown by them. Also if you've ever had a chance to really test them, by either resisting strongly or attacking strongly. I'm just looking for general experiences by anyone willing to share.
My current teacher is a 7th dan and I guess I can say that I've been thrown pretty hard by him in the past. I was just at a seminar with his teacher who is an 8th dan and I got the opportunity to be thrown around by him a couple of dozen times, too. I've also had the opportunity of being uke for a number of other 7th and 8th dan as well as a bunch of 6th dan.
Overall, these people are very, very effective in what they do. All of them have at least 20 years of experience with some over 40 years. Some of them have a wonderfully soft touch that's like being swept up in a wave at the beach. Others have an incredibly strong aikido that feels like I'm grabbing a live firehose. Some are as precise as a shinken is sharp. Others are as organic as my taking a breath.
When I've had the opportunity to grab these people with the strongest intent of not letting them throw me, some of them were able to throw me and others have a hard time. But, when it works, it's always pretty amazing. However, there's no doubt that all of them have had the ability to throw me and put me on my butt in one way or another.
As an aside, I did get thrown by the current Doshu (Moriteru Ueshiba sensei) about a year after I started when he was in the area for a seminar. Can't say it was much, really, since he was being really "nice" to me...