I think what he's trying to say is that the more expensive the tubing, does not necessarily mean it is "better". Some of the more expensive tubing is actually pretty stiff and will give a tougher ride, edging close to that of aluminum. It is a bit lighter, but is also MUCH stiffer. However, that's exactly what timetrial and racing people need.

If you're just doing fitness or triathlon, you'd probably be able to sacrifice 1/2 lbs and get a much more comfortable ride. With Reynolds, I think the only stiff "competition" grade steel is the 853. You can probably get away with a 600 or 700 series tubing and not see any change in performance, but a more comfortable ride. Reynolds 500 series tubing is still good stuff, but primarily found in entry to mid to upper-mid level bikes.

Personally, I think the most important thing is not only what the tubes are made of, but what the fork and stays are made of too. A lot of times you'll get a bike with 531 tubing, but that's only in the main triangle. The fork and stays turn out to be hi-tensile and that adds a lot of weight. Personally, I'd go for a bike with 531 tubes, fork, and stays over a bike that had like 653 for the main triangle but hi-tensile for everything else.

I talk about Reynolds tubing, but that's just because it was referenced earlier. A general guideline is that any Cro-Moly butted tubing is good.