Okay, why is it that your neighborhood amateur orchestras survive? My theory is that you have enthusiastic amateurs, often skilled, often not, who give their all into a performance. Sure, the strings are often out of tune, the woodwinds miss their entrances, and the brass flub left and right, but you don't go there to hear perfect technique; you go there for the music, which can transcend the limits of the performers when presented with enthusiastic magnetism, especially when the podium is bearing a talented, patient leader.
The Vienna Symphony was a mighty scrappy bunch when Horenstein made these recordings. But Horenstein was on the podium, and every player believed in him to the last man, or so it sounds. You have not heard Mahler's 1st until you've heard this incredible performance. Forget that the horns can't play in tune at all in the Finale; forgive the strings for their wildly undisciplined playing. It all comes together into a transcendental experience.
The Bruckner 9th I can't comment on in detail since I don't know it as well. All I do know is that when I listen to it, gee, it sounds well, short! Yet it gets its own disc, so I assume it is in the ballpark timingwise of other performances, and I enjoy it too. Same comments, btw, about the engineering and the orchestra.
The engineering: it's mono. It's not too bad. It doesn't hinder the performance, so I guess it is "open" enough. I rarely buy mono performances, but Horenstein's outings on Vox are an exception I'm almost always happy to make.