However, I am still very curious about what "increasingly difficult situations" might actually mean in one's Aikido training -- because this is central to our own position at our own dojo.
I checked out the page and the videos on your web site and I'd agree that you and I are both working towards more sophistocated attacks and how to deal with them. I'll comment more on that later.
If our training is somewhat intense, we often also come to mean being thrown hard, or dangerously hard, and/or being thrown "unexpectedly," etc.
My experience with Gleason sensei was that I was continually thrown "unexpectedly" and he would help me manage it a bit based on my level. I'm much more tuned in to what he is doing now, and much more able to manage to protect myself while dealing with the results of comming in at him hard and fast - and I still have to laugh at how I end up getting unexpectedly unbalanced and thrown. He's generally showing me what he is doing and I still have trouble expecting the results. That kind of experience is invaluable. It is VERY difficult for me to give to my students since he is MUCH better than I am.
About "what we do naturally" in ukemi: I do always give up balance for the sake of safety and/or honesty in the context of the martial situation. I think it that is only as natural as a child deciding to avoid a hot stove the "second" time. Someone told me about how there are 3 kinds of horses. There is the horse you have to whip over and over again, there is the horse you have to whip once, and there is the horse that you merely have to show the whip to. I'd perfer to be the unwhipped horse when I take ukemi.
With the constraint of that "rule" in place, I would say that taking Gleason sensei's ukemi (or anyone like him) is the best way to develop what I want to do naturally into what I do naturally. I do not believe too much in the "artificial ukemi" approach where people do comepletely scripted things - which does go on in some classes at the aikikai hombu.
Let us say that the highest reconciliation of Self required in ukemi or acquired via ukemi has to be the execution of what we can call the "pure" attack. It is that full engagement of oneself with no attachment to self, to the attack, the ensuing fall, the nage/uke distinction, the offense/defense distinction, etc.
I think that once you feel that you can protect yourself more reflexively you can start to push the "safety" envelope in a level appropriate way with your partner.
As far as the videos go, I liked what I saw. I am looking to develop something like that except I think I would want to incorporate a few other guiding rules:
-never (okay almost never) back up
-maintain your angle to keep the attacker out of 100% center vision
-actively take them in as you enter
(and as always don't play their game)