Most of it is simple, except for poe...
I've tried Seven Tongues, The learning, Next in line, 42147 from Poe... And they aren't "Holy Fuck!!" hard, but they are a challenge, i've got no idea about the solos except for 42147: theres two i think, can't remember off the top of my head, but they aren't impossible.
I used to much around with the acoustic solo from Deconstruction, that's a nicely written little section that... It's pretty easy to play on electric, but it is fucked on an acoustic like Jeff playes.
I only bothered with the riverdragon solo from DHIADW, it is simple too... it took a while to work out the sweeping bits properly, but other than working them out, it is a really easy song, including the solo.
What tomorrow knows is another easy song too... Nothing much too difficult on S/T album.
If you want a challenge to play... Go for poe.