Genre-crossing not old-school? I beg your pardon:
I'm just relating what I heard some other people back in the day say about it. Though I never played either of them, I did read them (I own both from way back), and I thought Barrier Peaks and Demonweb were both cool modules.
But I heard a few complaints about both of them for their elements outside sword and sorcery in D&D way back before D&D3 was even announced as coming soon. At the time, I got the feeling the complainers would not consider those two modules as true "old school".
For myself, of the modules in the poll, I voted for all as "old school" except
Dragons of Despair.
Bullgrit
Edit: For what it's worth:
"...I have received far too many comments panning the Q1 module ..."
-- E. Gary Gygax
http://www.enworld.org/forum/archive-threads/171753-gary-gygax-q-part-xii-4.html#post3023213
"...The Demonweb Pits were indeed envisioned as mze like, but there were to be no machines therein...."
-- E. Gary Gygax
http://www.enworld.org/forum/archive-threads/171753-gary-gygax-q-part-xii-4.html#post3024765
"the maze was fine, but all the rest, expecially the mechanical stuff, was not at all what I planned...."
-- E. Gary Gygax
http://www.enworld.org/forum/archive-threads/171753-gary-gygax-q-part-xii-6.html#post3029180
Maybe I'm reading too much into it, but it seems that EGG also disliked the steam punk aspect of Q1.
Edit more:
"The final portal is significantly different; this is the one that leads to the Spider Ship of Lolth. Yes, you read that right, a Spider Ship. If the idea of science fiction intervening into your fantasy universe puts you on edge, you're not going to be happy at all. I didn't like it, but some people from all accounts completely hate this."
http://www.rpg.net/reviews/archive/13/13662.phtml
"So, for example, Lolth's having a giant, steam-powered, mechanical spider ship never bothered me the way it bothered many people."
http://grognardia.blogspot.com/2009/02/retrospective-queen-of-demonweb-pits.html
"A giant mechanical spider is the best they can come up with for this cosmic place? Sounds more like a modern Hollywood take on things.
Maybe having had it been a gigantic living spider I would be "now you are talking!" But what, the Godly realms have all this damn steam punk stuff, then? Or Lolth is the only being blessed with robotic technology? Jeez..."
http://grognardia.blogspot.com/2009/02/retrospective-queen-of-demonweb-pits.html