All steel alloys are essentially the same stiffness, its wall thickness and diameter that makes the difference, and wall thickness is much of a muchness with above mentioned tubes. It is perfcetly possible to build a bike that is far too stiff from tubes available to us today, dependent on compnent choice. However, with the availability of good quality higher volume tyres, the definition of too stiff has moved. A 54cm frame, with 44mm dt, 31.8st and tt, 18ss and 17x30cs will be (ive tried it) unbearable on 28c tyres at 100psi, to the point that I wouldnt want to ride for more than a few hours, but will be amazing as far as power transfer is concerned. However, the same tubeset built around maybe 40c's, or even 650b x 48 tyres at low pressures, will be perfectly comfortable for a long time in the saddle, while still very stiff (once tyre squirm point has been passed). The biggest thing to effect frame design in the last ten years (in my opinion) is tyres. People like to make a lot of noise about tubes, but the reason we choose specific ones is nothing to do with shape or alloy, but but length, wall thickness, shape and how hard they are.