I think the Eschenbach M6 is terrific. Great playing, conducting, sound. I've had the privilege of hearing him live several times and I've never been disappointed; I don't understand why some people just can't stand him. But that M6 should put to rest any thought that he's a second-rate conductor.
Yes, a lot of the credit for the orchestra goes to Curtis, some to Temple. But there are quite a few players from other places, too. But sadly, a lot of the fabled Philadelphia sound was also the result of the work of two conductors: Stokowski and then Ormandy. Since Ormandy left, the quality of the orchestra has definitely suffered. They're still quite good, but the once-common list of the Big-5 American orchestras would no longer include Philadelphia. Too many top-notch virtuoso players (especially the winds) have been lost - mostly due to age. They've had too many music directors who don't spend enough time in the city. That's the way it is everywhere these days. Like most orchestras, they no longer have a distinctive sound. In recordings from the 60's the orchestra was instantly identifiable because of the wind soloists. Guys like Bernard Garfield and John DeLancie aren't all that common! Too bad they didn't record more Mahler back in those days, but then Columbia was letting Bernstein do that in New York, and Ormandy wasn't an especially great Mahler conductor.