This may sound like a cop-out, but it is what I firmly believe: The builder and the intended use counts for much more than the tube set. My Paramount is Reynolds 531, my De Rosa is stickered Columbus SLX, but there is a fair-to-middlin' chance that it has an SPX downtube because of its size.

I do not know what the tubing is on either my Ron Cooper or my Eisentraut and, as I have said elsewhere, beyond curiosity, I don't much care. Both are almost certainly a mix based on the knowledge and experience of two of the very best frame builders ever to hold a torch. Even though neither of these frames were built specifically for me, I am not about to question their choices, especially since they are such joys to ride.

I have also had and enjoyed frames made of Ishiwata, Reynolds 853, Miyata proprietary triple-butted, True Temper and another SLX frame. All the differences - and they were all different - are more clearly a result of different frame geometery than anything obvious in the tubing itself. I don't for a moment doubt that there are differences among the tube sets, not to mention differences between different thicknesses of otherwise identical tube sets. But design seems to me a much more important variable in most cases. (Notice I said "most" cases - I would not want Max tubing on a touring frame, for example.)

As for modern steels, from what I've heard it sounds like Reynolds 953 is pretty damn trick. 'Spensive, though.