Barry, my copy arrived yesterday and I think you're absolutely right about the trio sections in the scherzo, they're amazing! The woodwinds are in fine form and the sound engineers did a wonderful job capturing the acoustics of the Grote Zaal. I also think Kleiter is singing from behind the orchestra.
The tempo for the third movement feels just right, Gatti never wallows in slowness, if fact, his rendition of this movement reminded me a lot of the beautiful Kletzki recording with the Philharmonia.
I've only listened to it once, but I think I like this RCO M4 better than Mengelberg, Van Beinum, Solti, Haitink 1 and 3, Bernstein, Chailly and Jansons. I also love Haitink 2 (with Roberta Alexander), but Gatti has a bit more character.
Among recent recordings, I would rate it much higher than Tilson Thomas (talk about wallowing in slowness..) Zinman and Honeck, but not Fischer and Stenz (I haven't heard the Macal yet). Of course, it's not a competition, but it's aways fun comparing..