Sorry for the delay in responding. We actually just put out our new zombie-themed album today so things have been crazy.
To answer your question, in our experience, haunts just like to mix things up. Sometimes the world they're trying to create demands more rock/metal/industrial-edged tracks. Other times they need to create a "party" atmosphere as someone mentioned. In some instances simply sound effects in lieu of music is more effective. One thing that has changed since we first started is that most haunts are much more aware of sound, music, and how it impacts their attractions. That's a good thing for everyone.
To answer another question -- We've had a great relationship with HHN that remains strong to this day. Might there be an opportunity to work together in an even bigger way in the future? Maybe?
Thanks for all of the compliments! We appreciate it.
Edward Douglas
Midnight Syndicate
www.MidnightSyndicate.com