Since the flexibility of most all steels is the same it is the tube diameters and wall thicknesses that control/dictate the frame's compliancy. For the same wall/diameter tube spec a frame made from HITen tubing (remember the 1020 stuff Raleighs used) and 753 will have the same feel". Now of course that HiTem frame will very likely not share the more sporting geometry or components or rider fit as the 753 one has. So these types of questions are most always never really understood or answerable.

Don't confuse the qualities of strength with those of stiffness. They are quite different and stiffness that counts more only till the frame is stiff enough to keep the parts away from each other and the wheels in roughly the same tracking planes. After that it is strength that allows less material/weight.

Back in the day we sold the alloy steel high end bikes with the "promise" of being more resilient then the low cost mild steel bikes were. We understood an important quality was not getting beat up while we rode our miles. Andy