Joe,
Here we go with tubing discussions again. This is a topic that is "interesting" and for some perhaps "informative", but if anyone is expecting a concrete conclusion beyond the opinions of the framebuilders involved then at least it won't be me that will supply it. My opinion still is that the framebuilder and his/her techniques are responsible for the end resulting "ride" that we all seek to define. The nebulous term "ride" of the bike will always remain so and each persons' opinion of what it is and what they like will remain a mystery to "science".
"Super Vitus 971" is the Vitus tubing I remember. Only used it once or twice in my 30 years of building. It is chrome moly just like Columbus and I classify it as such just like Dave does. I've never had raw Falck tubes nor do I know the composition of it, but like all other "quality" tubes sets it works fine in the hands of anyone who can build a good frame. Like I mentioned, I've seen plenty of Cinellis (both Mod. Bs and Special/Super Corsas), and a few Masis that were either all or part Falck tubing. Personally, I don't think Falck tubing was any lesser quality in reality than say Columbus, but I'm pretty sure it was less expensive and therefore found it's way into the "second line" frames from top makers as well as frames that were not exactly "top line" like Frejus. Like Joe says, these frames are not really lesser bikes but are "less expensive" primarily due to the components.
Regarding use of Reynolds 531 vs. Columbus and mixing same in custom frames I personally make those choices based on tube gauges for any given part of the frame depending on the use intended and rider involved, etc. In addition to that I often consider the cross sections and diameters of the fork blades and seat and chainstays from both a performance and aesthetic point of view. I prefer double taper seat stays pretty much exclusively primarily on account of how they look. I'm sure they don't make any significant difference in the "feel" of the frame. Like Dave said, if you can tell the differance between one tube (equivelent gauge) and another then you most assuredly have the worlds' most sensitive ass. I can't tell. What one feels as differances is all to do with the design, fit, construction methods, and WHEELS and TIRES if the only other difference is the tubing (within reason). Don't like the way your bike rides, look into your wheels and tires first!
From a technical and workability standpoint the differences between Reynolds and Columbus tubing are like Dave explained. I believe overall the Manganese Moly combo is generally better for bike frames; espically if one chooses to braze lugged frames with brass. It's less of an issue when silver brazing. Fillet brazing with brass is not as much of an issue either because of the significantly lower temperatures involved.
I don't know if I covered all of the questions but there's at least some of it. I can't always keep up with all of this; especially having to sort through multiple multiple forwards until my head spins.
Bottom line is I prefer either Reynolds or Columbus and I make my selections with the aid of my "Magic Eight Ball" as to when and where to use each. Every time I ask if Columbus is BETTER than Reynolds the answer is always "it is doubtful". OK, I'm now going to fold up my "Sacred Framebuilders Robes" for the evening and chill out. (Hope you like that one, Dave)
Just saw Stevans' post about frame sizes. Both companies make tubing to accomodate larger frames. My opinions are not to do with the "ride" of the frame per se. My opinions have to do with what my customers say about what I build for them. What I think of my frame does matter in the least. How my customer feels about their frame is the ONLY thing that matters. My experience has been that with careful selection of tubes and an experienced designer/craftsman on the other end of the tourch and file an excellent frame can be made in any size. My friend still has the 66cm frame I built for him in 1984 out of a selection of tubes (the only thing I remember for sure are the PS chainstays) and he still loves it. Won't sell it despite getting offers periodically and having had me build a frame from ELOS later on. Go figure!
Brian Baylis
La Mesa, CA