I know these two recordings are an old topic now. I've finally, FINALLY had the opportunity to hear them. They're both very good, obviously, but I think the Bernstein/Cleveland one is truly special. I think this Cleveland one is just as good as his original N.Y. one for Columbia, even though the sound quality isn't the best.
Anyway, between these two recordings,
Tennstedt obviously has the better pipe organ. I like Bernstein's mezzo better (who is she?). Also, the Cleveland gongs - both the low and high pitched tam-tams - sound a bit small (and thus, high pitched). But, there's that certain Bernstein magic - in spades! And, although the Cleveland trumpets are a bit too close to the microphones, the Cleveland low brass section is to die for. As a tuba player, I LOVE Ron Bishop's playing.
During the Dohnanyi years, Ron Bishop was forced to use a smaller tuba (a Miraphone 184, I believe). But here, you get to hear him on his excellent, old Alexander. If you think I might be exaggerating R.B.'s superlative playing (or don't think it's an important point), just listen to him on the Cleveland recordings of Prokofiev's "Cinderella" (Ashkenazy); "R. & J." (Maazel); Prokofiev's 5th (Maazel); 6th symphony (Ashkenazy), or the Respighi "Roman Trilogy" (Maazel). Trust me, you'll soon dig the difference.
Anyway, regarding the Tennstedt M2: yes, it's very good - better than I had expected. But I still prefer the performance he gave at R.F.H. in 1980. The tempi in that performance weren't quite so exaggerated (nobody does exaggeration better than Bernstein!). Interpretively speaking, it was closer to his EMI studio recording. Still, good is good. From here, I'm very much looking forward to the Paavo Jarvi/Frankfurt R.S.O. M2 that'll be coming out on Virgin Classics.