I am able to fit to a wide range of bikes so "fit" isn't much of an issue, but I know the Reynolds frame is a perfect fit and I assume I can fit Al and carbon as well. Seems like steel is the way to go, especially as I have a strong romantic inclination in that direction anyway. After all, all 4 of my current bikes have Brook's saddles.

So am I correct that aluminum and carbon are primarily for lightness and cost and the downside is lack of stiffness and earlier fatigue? Have I got the gist of it?