I think patrickgeekhack stated it correctly. We are not trying to not bottom out. I actually bottom out the keys most of the time but lightly. But when you get the grove and you are not bottoming out the keys the keyboard has a completely different feel to it. If you think describing a Topre switch is hard describing the not bottoming out grove is even harder. It is like the Topre switch changes mode or something and it just feels so good. It makes you understand that "Good feeling of oneness with cup rubber" saying printed on every Topre box.
I too have had this experience. I often bottom out the keys of my Topre. Especially when I am just intermittently typing. But there are times when I'm doing a lot of typing and I just get into the proverbial "groove" and it makes the 103U sing, typing-wise. It's a beautiful thing! And it's hard to describe.
I love my 103U. I read something about "taking the red pill" somewhere, briefly, and I assume that this means that, like in The Matrix, once you do that, you can't go back. I sort of feel this way about the Topre switch. It's turned things upside down for me. I'll definitely cycle my Model M and AEK II back into rotation, and see how I like them after a week or so of use, and I'm going to get a Cherry MX blue board also at some point, but I suspect that, sadly, I have gone down the rabbit hole and am only going to be really satisfied with a Topre keyboard from now on. We shall see.
As for rubber domes and paying a lot of money and psychology, I have to say that:
1. There's rubber, and there's rubber. Many different kinds and qualities of rubber. And the stuff they use on the Topre must be pretty darned good! Or at least it feels that way. I know they spent a lot of time on the design of the rubber dome. And given the high quality of all the other parts, I suspect that the rubber is also very high quality.
2. Two or three hundred dollars isn't really all that much money if you spend hours every day at a keyboard. Some of us spend as much time at a keyboard (or more) as most people spend watching TV. And people think nothing of dropping $200 or $300 on a TV. It all depends on your particular usage patterns. If you only hunt and peck to type in an occasional URL or to compose an email, well, then, yeah, a $300 keyboard might not feel like that smart a buying choice. But if you type hours every day, that is a different story.
3. I don't believe that the notion that spending a lot of money on something necessarily biases you to like it. It can often do the opposite, in fact. And, for many people, they know they can turn around and sell the item without too much of a loss, so this sort of negates the "maybe I like it more just 'cause I paid so much for it." It all depends.