That question I cannot address too intelligently because at the time I was still largely in customer mode and just starting to get involved in the business as well as branch out to buying around the country. Plus of course back then we did not have the wealth of highly transparent national availability that we do today.
What I can say is that for the areas and stores I knew best- yes there was often a strong reliance on Theise and Weist to cover Germany as a category. But those retailers who relied on it and paid little attention were also more focused at the lower end. I had no trouble finding and obtaining all the von Schubert wines I wanted- and for the most part within Texas- from retailers that took the care to stock the wines. In that sense, perhaps one could compare von Schubert to, for example, Chateau Ausone. No, there were not many places in Texas where one could buy Ausone 20-30 years ago, but the wine sold quite quickly where it was offered to a very grateful core group of aficionados.
As for Texas collectors in general (which was my entire world of knowledge at the time aside from alt.food.wine)- at least to the extent to which I knew them and their favored estates either personally or through acquaintances of my father- in the time before von Schubert disappeared from the market for a while, there were three German wineries that were avidly collected and cellared, and revered above all others. Those were Egon Muller, JJ Prum and von Schubert.
One other interesting data point which I did not mention earlier because I cannot remember precise numbers- in the very late 90s or early 00s (soon after the website replaced the periodic mailers), Premier Cru offered 1959 von Schubert Auslese for an astonishing price. If I recall correctly, it was around $1,000 per half bottle and $2,000 per bottle. At the time it was a DRC price- Romanee Conti was just passing the $2K mark for any vintage in the secondary market. And the bottles sold! I have never forgotten that because the number was so incredibly high and also because it was the first time I had ever seen von Schubert that old offered for sale.
Point being- all the evidence I have, much of it anecdotal, is that once upon a time von Schubert was very clearly considered among the greatest wineries in the world, and certainly in the very top ranks in Germany.
One other thing I would note now that I have had a day to think on this thread, here in the United States I think there have been three great boosts to interest in German wine in our generation- meaning times when a lot of new collectors got interested and started buying. First came the 2001s, and there interest was driven largely by the high quality of the vintage itself.
Second was the 2007 vintage, and at that point there was not only vintage hype but we had a thriving national market and stores like Chambers and Crush joined Dee Vine in being major national players who were not only carrying the great estates of the day but introducing many wineries to the US for the first time. This was also the time when specific wineries also really started to get a lot of attention in a more sexy-celebrity sort of way- Donnhoff, Keller and Schaefer-Frohlich for a start, and also Willi Schaefer and AJ Adam.
Finally, you have the 2015s. And here an additional factor comes into play. You have a great vintage. You also have increased retail distribution of the wines to the point where even more- and larger- retailers are carrying and promoting the wines. But now you also have a market in which wild speculation has run deep in many markets, and is now turning to Germany. It is visible across the board- stricter allocations, higher prices, and most notably- a highly unusual broad and strong upward trend in pricing at the annual auctions.
Von Schubert missed out on those first two booms courtesy of not being much of a presence in the US market when they happened. That brings, I think, something of a disadvantage coming into the present. But from what I have seen and tasted of late, I imagine that disadvantage will erode pretty quickly. While I certainly hope I do not end up spending a king’s ransom for them- the upcoming Mosel Trier Auction could be an important indicator for the future. It is a great Auslese vintage and von Schubert has both a GK and a LGK Auslese in the auction, which will be their fourth auction since returning to the VDP and the first time in that period that von Schubert has offered an Auslese with a GK or LGK designation.