All due respect to previous posters, there are many grades of Tange-branded steel; the same is true of Colombus, Dedacciai, True Temper, etc. Just like Reynolds has been available in 501, 531, 631, 725, 853, etc..... I've found that, as a bigger guy, i typically don't like the top-shelf stuff with the extremely thin walls, but they are undoubtably better for the right riders. They feel whippy, to me.... But, i just wanna say that some of the most impressively light frames from the 80s that's i've ever encountered were made from Ishiwata Quad-Butted. Online research suggests that Ishiwata made heavier and lighter versions of their quad-butted steel, for different applications, so maybe they're not all that lightweight.
By no means light, though, is the triple-butted and splined tubing that Miyata made themselves for their own bikes and for other marques that they produced bikes for (Univega, some Koga bikes, etc...) I mean, yeah, it's a lightish tubeset as compared to bargain-basement stuff, but the butting wasprobably more about strength than it was about weight savings. Every Miyata I've ridden with the triple-butted splined steel felt great; responsive, stiff, light, and just good quality. Any Miyata road frame with downtube shifters will be a very nice bike; really good finish, well-constructed, just awesome. They sold some track frames, too.... kind of a grail bike for me (but I'll probably just sell-out and buy a modern Panasonic track frame....)