Ambient sections are awesome. It's definitely something where it's application and presentation is very important, otherwise it'll be what we could call a 'momentum killer'. I don't think this happens in any of the Dream Theater song examples though. Also I'd never consider that these sections make a song too long. Or that the epics are bloated or 'self indulgent'. I remember a Geddy Lee interview which defended the idea of 'epics' and long songs in the sense that himself as a composer, never found it to be a kind of self indulgence or act to show off, but more considered the excitement in creating a concept that had bits and pieces that could be fitted together like a puzzle. It was just 'typical boyish enthusiasm' having fun constructing these ideas just happened to result in these 20 minute long songs. They never set out to deliberately try and be better or longer than the preconception of 'normal' songs, it is what it is, and whatever.
Anyway, back to DT. Illumination Theory, the Orchestra section was just
at first listen, and the ambient section preceding it, allows the Orchestra to subtly come in quite naturally in the context of such a 'full on' song. On First Impression it was probably one of my favourite moments of the album.
The Count of Tuscany's bit works aswell, the musical foreshadowing of upcoming melodies is fun but most importantly it's breathing room, up and down, acceleration and decline, tension and release. I mean the comment about A Change of Seasons kind of flowing like a sine wave, it still applies to these other examples where the 'flow' has polarising elements that were intended and necessary for the song. Of course you can focus on one side of the coin and even write a song that only focuses on one aspect (like the kind of the non stop relentless thrashy songs that most modern metal seems to stem from). But I think these sections all have their place in DTs music.
In The Presence Of Enemies break is easy enough to defend because the break was deliberately used to bookend the album. It's a presentation thing and maybe, for all we know this break could have been considered a 'momentum killer', but even if it was, the way it's presented doesn't have that effect unless you intentionally put the 2 parts together and personally feel that way. Also, I think you could argue that the change in tone relates to the storytelling elements of ALL of these songs, this song being no exception.
Six Degrees Of Inner Turbulence NEEDS Goodnight Kiss (or something like it) after The Test That Stumped Them All. Whether you like or appreciate the lyrical content or not doesn't matter. If the song was going to be any longer at that point, it needed to adjust itself to balance things out. Although I can understand it not being universally accepted because I've had music playing in the past, had a friend comment on Overture saying how amazing it sounded. By the time About To Crash came on I literally got a comment from the same guy blatantly expressing how much he thought the song sucked. I told him it was the same song that was on 5 minutes ago and he established that "they really let that one turn to shit". By the time War Inside My Head came on he said something along the lines of, "this is more like it, much better song than the last one". I told him it was the same song and he was a bit like
. By the time it got to Goodnight Kiss I didn't hear a word out of him but he could very well have been thinking that he didn't like it.
Octavarium. This one's weird because it's definitely better as a sum of a greater whole. Including the context and indirect concepts of the album in general. It took many listens to grow on me, and some of that appreciation came from being aware of certain elements in it's writing and composition that don't come across unless you analyse the song on different levels. Now, you shouldn't HAVE to do this to appreciate a song, but if this sort of content helps increase ones enjoyment of the song then ultimately there's nothing wrong with it. It just might not click with some individuals.
I think Illumination Theory is the ultimate epic for DT. It not only stands out on your first listen (like TCOT), but it has a lot of subtle bits that you wouldn't notice at first so the song can grow on you without getting repetitive. It's clearly had a lot of thought put into it's arrangement and it feels like it has something happening on a different level like Octavarium, puzzles to figure out, which gives it some intrigue and mystery. It's also a grower like ACOS in that it seems to get better the more I listen to it. I really think it's the perfect summary of everything that Dream Theater is good at. It does everything well, including the silence. Yes even the silence at the end before the outro seems to be the perfect amount of time.