[Hillster]

A double top is two thin layers of wood with a nomex core that is in a honeycomb pattern. Most of the inner core is air. The honeycomb is just the structure to hold the two layers of wood apart. To confuse this with plywood is reaching for the stars. This creates a top that is much lighter than solid wood.

The plywood people refer to when they are talking "bad for top wood" is the cheap low grade stuff used in entry level guitars.