And it looks like my account has been activated! Hello NeoGAF, I've been a LONG-time reader of the forums.
Actually there's ~105 minutes of orchestra in the score. It's just a case of the orchestra not being the featured element for the whole soundtrack (which is often the case with a lot of soundtracks). It's also a case of the fact that the orchestra isn't a gigantic megaton orchestra. We used 2 different sizes for the game. One would be considered a chamber orchestra of 22 strings, flute, clarinet, oboe, and piano. The other was more conventional, with 40 strings, 3 flutes, 2 oboes, 3 clarinets, 4 french horns, 2 tenor trombones, 1 bass trombone, harp, piano. The chamber orchestra was used for about 75% of the game, while the bigger group was used for... yes... the bigger scenes (ending, chase sequences, etc...)
A lot of people call Ori an orchestral soundtrack, and I'm OK with that, it's the glue that holds the thing together along with the main theme. The orchestra is there, weaving in and out, but what gives each area its flavour is all the other 'stuff', the ethnic winds, in Ginso Tree all the wooden percussion sounds, and so on. Ori is as much an orchestral soundtrack as say... Life of Pi, which has a ton of synth work and world music instruments in its score (obviously from India) that gives the score its unique sound.
As for Misty Woods, you nailed it. I chose the whole-tone scale simply because it's impossible to resolve the whole tone scale, thus if the music isn't resolving, and you're in a place which is weird and constantly in flux, it should help with the disorientation. It's my view that if you end up being confused at times in the Misty Woods, then we did our job!