I would bet that frame geometry and tube selection for that geometry is as important, or more important, than tubing material, itself, once you graduate up from "gas pipes".
Wheels are 100% more important than frame, even when comparing gas pipe frames to 531 (gas piper with tubulars versus 531 with steel rims, straight gage spokes and heavy, 60 psi pressure tires). I would venture to guess that good ergonomics and great brakes come next in importance after the wheels and then good gearing (or are gears part of the ergonomics?). Get all that worked out and we can discuss the benfits of the various steels.