You might be getting ahead of yourself. At this point, I'm not so sure that there's a committment to finish the entire cycle. There have been a lot of changes at Telarc, and they're now being distributed by Universal - the same folks who oversee DG, Decca, and Philips. They still have M2, M7, and M8 to knock out yet.
I'm afraid I don't quite share the same level of enthusiasm for Zander's Mahler as you do. Yet, I do have a feel for what you're getting at. But I think that there are basically two problems here. First off, the Philharmonia of today strikes me as being nowhere as good as it was in its glory days under Walter Legge's demanding control. Oh, they can play all the notes alright. But they strike me as being very thin in the bass end of the orchestra. You can hear a great example of this on the very, very last chord of M3 - you can hear the third and the fifth of the chord very clearly, but the "D" in the bass is almost missing. In addition, they're percussion frequently underplay very basic things, such as cymbal crashes and bass drum strokes. I know that that might not be such a great priority with you, but it does bother me. Granted, some of that may have to do with recording venues and microphone set-ups. In Legge's day, the London orchestras still had access to the outstanding Kingsway Hall. That's no longer the case, and there still isn't one oustanding concert venue in London today. Yet, I still get a sense that today's Philharmonia tries too hard to finesse everything. The old Philharmonia was a much more rough and tumble sounding group; but without the wrong notes, counting mistakes, and poor intonation that one frequently encountered on the European continent in those "post war" years.
Here's the other problem: not unlike MTT, Zander sometimes makes things worse by being so didactic. For example, in M3, he makes a big issue about the posthorn solo coming out of nowhere; sounding in the distance. But as a result, the posthorn is practically inaudible on his recording. Unless you've already been playing the recording pretty darn loud, you have to run over and turn it waaay up. In M4, he makes a big deal about finding an appropriate sounding singer. He finds one, OK (I forget her name), but she's so bland and generic sounding that his point becomes totally lost - or pointless. Also in M4, he makes a huge deal about some of the initial tempi issues in the first movement. Yet, here's another example of losing the forest from the trees, as he doesn't think to pick up the tempo significantly at the start of the development section. Compare to this Norrington, even, where Roger at least recognizes that the development section should be as fast - or slightly faster - than the movement's initial tempo. As a result, Zander's development passage, and its concluding climax, fall flat as a pancake. That might not seem an obvious thing to you, but just compare the same several minutes of music with Norrington. There's a world of difference.
Yet, on the other hand, I think I know what you mean, as there are some very, very good moments in Zander's cycle as well. I like the fact that he makes the majority of the soft percussion in M5/1 - played under the slow funeral procession - rather audible. I like the way he balances his brass at the climax of the long brass chorale towards the end of M3/6. For the most part, I think that his "live" M9 is quite good. In M3, Zander was unhappy with the results that he was getting with the first movement, so he decided to redo the entire first movement in a single take. As a result, it comes off pretty darn good. One wonders if he simply shouldn't have tried that more often.
There's also a very false claim in regards to Zander's M6. They used to add a blurb on the front cover, claiming that this was the first recording of Mahler's first version. That's not entirely correct. In fact, it's not even remotely correct. As you may know, he includes two versions of the finale: one with the third hammerstroke, and one without. On the version that has the third hammerstroke, Zander does use the first version for the few bars that surround the third hammerstroke - both immediately before it, and immediately after it. The differences aren't huge. But, the rest of the finale on both versions is clearly taken from the revised score. To the best of my knowledge, with the possible exception of F. Charles Adler, nobody has made a recording of the entire first version of M6. All of this may not be a big deal, but I just don't like the false claim being plastered all over the front.
There's one other odd thing. In the scherzo of the M6 - towards the end of it - there's a spot where something percussive happens, that sounds almost exactly like one of the hammer blows from the finale. I actually thought it sounded kind of good, and sort of appropriate. I e-mailed Ben. Zander about it, and he assured me that there weren't any gratuitous hammerstrokes. Yet, when I pressed him further on it (very politely), describing the sound and its location as objectively as possible, he refused to acknowledge or answer. Most odd, because something's clearly there. I listened to it over and over on my best headphones, and it really sounds like wood on wood.
Anyway, I don't want to be a downer here for you, but don't get your hopes up too high. With Universal in control of Telarc now, there may be a lot of odd and major changes for them. At the very least, they're going to take their sweet time in finishing this off.
Barry