Did you or your contractors use the lighter sheetrock (drywall) now available? Pros and cons you have experienced or heard about?
Lightweight Gypsum Board:
US Gypsum Sheetrock Ultra Light
National Gypsum Gold Bond High Strength Lite
As far as I can tell it just weighs less but has trouble achieving the same fire ratings as normal weight board so I guess it's for the single family home market. The more important issue is the STC rating.