Hi Eric. I went back and listened to the Netopil M2. It's certainly very well recorded. The ending is mostly quite good, but I would like more of a real pipe organ. Also, I think the very last note of the symphony could use more of a crescendo, which is something Bychkov did well. But I do have two other things that really bug me, both having to the do with the final climactic passage of the 'march of the risen dead souls' section of the finale.
Where there's a series of offstage trumpet fanfare figures - those are supposed to come in closer as they go. Soooo, at the last time the offstage trumpets play there, they're supposed to be close enough that you hear their rapid descending scale lead right into where the entire orchestra comes back in, tutti (and fortissimo). To be fair, Netopil's isn't the only recording where that's a problem - not by a long shot. But if the trumpets aren't clear and audible there, it just sounds like an empty hole. But what also bugs me is that the rapid series of tam-tam strokes at the end of that same section are pretty much inaudible. They're somewhat audible on the Bychkov. That's unfortunate, because the tam-tam playing at the climax of the Scherzo movement is really good.
That said, though, Bychkov does much better with the passage in the Scherzo where a trio or quartet of trumpets start singing to each other. It's a passage at a slower tempo. Bychkov makes a real meal out of it. Also, aside from the climactic passage, I like Bychkov's Scherzo better in general. I think it's more animated and has more character.
Perhaps what Netopil really has going for him, besides really good sound, is that his performance does really flow well (as you mentioned) - which is a feature I really like about his M3. As for the Vanska series, I like those better when I play them back on my SACD player (but in the two channel mode, as I don't have 5.1 Surround). The M2 sounds pretty darn good when you play it that way.