If you like prog bands with thicker grittier (yet still melodic) vocals, check out Suspyre and Vangough if you don't already know them. Suspyre's best two albums are A Great Divide and When Time Fades, and Vangough's is Between the Madness.
Wow - thanks for the suggestions. I listened to some of Vangough's songs and I really like what I hear so far - reminds me a bit of PoS' good times and I really like the singer.
As far as the musical prowess discussion, I am really not in the place to judge that because while I play a bit of guitar, I am not on a level (by far) where I can really start to differentiate on how difficult some of the stuff really is to play
But referring to Dream Theater vs. Symphony X, my take is, that DT was and is technically still really good, but they have IMHO mainly lost the ability to create tight and meaningful songs and instrumental parts.
When listening to their last albums, I find that I always have two problems: Even when there is a good idea for a song, it is like they wrote the song and then started breaking it up to add instrumental sections here and there that sometimes just seem to have no connection to the song and/or to each other. Most parts/songs overstay their welcome for me and I start to get tired of the songs and the meaningless wanking just for the sake of it.
In addition to this many of the instrumental section start to sound alike - "same old" breaks and feeling and especially Rudess seems to repeat himself quite a lot. As an example, every album has a "circus/rag" part of his and while it was a cool idea and well implemented on Scenes From a Memory, it just makes me roll my eyes when they do it on later albums, because it is just a rehashed idea repeated over and over again.
This never happened to me with Symphony X so far. Every part of their songs has it's place and is integrated with / stays close to the idea of the song (with just very few exceptions, which is no big deal imho). I always have the feeling that every part has meaning and identity - it has an idea and a focus and plays a part in the structure of the song that serves the "arc of suspense" of the song.
So to sum it up - while the technicality of these bands evelate them into excellency, for me its more about the song and if I can relate to it or not. And when both things come together, it creates a thing of beauty, which is what Symphony does for me constantly!