re: the original post.

most of us have at least a few we wish we could take back.

Looking at trail/rake/angles on different bikes and comparing them to discuss handling makes my head hurt.
Too many variables.
Just changing tire size changes two of the variables.

https://www.kreuzotter.de/english/elenk.htm

I don't know about "twitchiness," although I've heard the word used to describe track bikes on the street.

I know my Bianchi Pista feels stable at the highest speeds I can hit with it, probably well short of 30mph.

My Pista also feels wonderful at very, very slow speeds.

And then, at normal cruising speeds (19-20mph for me), it seems to pick its way through the road debris without any conscious effort on my part.
I also note I can "throw" the front wheel sideways, although I know the wheel stays in contact with the road.

All of this said, I would never think of taking my hands off my Pista's handlebars.

Someone brought up weight distribution, or what I would call Center of Gravity.

A bike has a center of gravity around the rolling or leaning axis, but it also has a center of gravity around the yaw, or turning axis.

I have a 35mm setback seatpost, and this puts me further back over the rear wheel than most folks.
I wonder how this changes things.

Wonder no more. It's going to move more of your weight towards the back wheel, although the effects in terms of overall weight distribution are probably negligible. Here's a fun game for a rainy day: take a bathroom scale (or two), sit on your bike and weigh the front wheel and the rear wheel. Switch from a straight seatpost to one with setback, repeat the process and see how it affects things. I doubt much will happen.

FWIW, "ideal" front:rear weight distribution is usually around 45:55 or so.

I find various track bikes and various touring bikes to be both difficult and easy to handle no-handed and at high and low speeds. I don't think there's one golden variable that makes one type of bike this or that way in certain situations. It seems like a skilled rider can do exactly what he or she wants if he or she knows how the bike might respond to very particular movements.

All of these conversations are completely academic... but still, I think it's interesting to know how this stuff works in theory and then see how well theory conforms to practice. ie, for the frame I just made myself, I started with the measurements of my 3rensho and tried to achieve certain results by adjusting some elements of the geometry while leaving others well enough alone. Also, in cases like Queerpunk's wacky Pogliaghi, I like being able to listen to his account of how it handles and then think about it in terms of how the bike is designed. You're right though, as in almost all cases the engine is the most important thing and a skilled rider can make any bike work to certain extent. On the other hand, it's definitely an oversimplification to think that there aren't specific things that make "track" geometry different from "cx" geometry. Anyway, I'm rambling.

Yeah, it's all pretty fascinating, I really was interested to learn how headtube angle and rake interact. Especially how they affect steering quickness and stability which I am pretty sure are different.