I really need to re-hear the Stoky M8. I wasn't that crazy about it the first time, for which your indicated fast tempi may have something to do with. But this statement is a 'red flag' for me as well: "I don't recall any recording of M8 where the female soloists sing with as much emotion and conviction".
I don't want the women to always sing with lots of emotion and conviction. I do want Soprano I to belt out the end of her BIG solo near the end of Part II in good Wagnerian fashion (before the offstage soprano part, followed by "blicket auf") - you know, the business about Faust's anticipated redemption ushering in a brighter day and all that jazz. But as for the 'three penitant women', I want to them to deliver the text in a fairly non-obtrusive way and permit us to hear Mahler's exquisite orchestration behind them. In fact, if they sang their parts from the next county, it wouldn't hurt my feelings. I don't want them 'emoting' on top of what's already an over-heated text.
As for Part I, I'm of the opinion that the vocal solos are usually sung too closely to sound like 'distant planets and stars', and too close to each other as well. I think that the soloists (in Part I) should be dispersed widely apart amongst the two adult choirs. Since that's not practical (they need to be more 'up front' for Part II, obviously), I think they really should be spaced widely apart behind the orchestra (at the front of the choir) - but just for Part I. In my opinion, they shouldn't sound like an ensemble, but rather just as Mahler said: distant stars and planets.
The opening baritone and bass-baritone solos in Part II should sound quite 'Wagnerian', but then the music makes a sharp turn towards Mendelssohn. Again - just speaking for myself - I don't want the short female solos to sound 'over wrought' until we get to the above mentioned Soprano I solo. The two big tenor solos are very difficult, and yet they should sound quite 'helden tenor'-ish. For me, the two big tenor solos are very key in judging the overall quality of any M8 recording (it's not 'make or break', but it is a critical element). I don't remember anything about Stokowski's tenor.
Regardless, I will give the Stokowski M8 another listen at some point in the near future. That much we do owe you for your time and fully informed opinion (I just have other priorities within M8). I know you're correct in stating or implying that it's a 'milestone' recording - there's no denying that. And who knows: maybe I'll end up liking it better the second time around, or at least appreciate it for its strengths.