YES, models my be flown to any height by "Academy of Model Aaeronautics" members under guidelines of a "safety program".
In January of 2016 the AMA requested that the FAA clarify the 400-foot issue in writing. The FAA's response recognized AMA’s role as a "community-based organization" and acknowledged the AMA safety program, including allowing flight above 400 feet under appropriate circumstance.
In this letter, dated July 7, 2016, the FAA states:
"…model aircraft may be flow consistently with Section 336 and agency
guidelines at altitudes above 400 feet when following a
community-based organization’s safety guidelines."
"Community-based organizations, such as the Academy of Model
Aeronautics, may establish altitude limitations in their safety
guidelines that exceed the FAA’s 400 AGL altitude recommendation."
This letter confirms that sailplanes, large model aircraft, turbines, and other model aircraft can legally operate above 400 feet if the AMA member is operating within the AMA safety program. The FAA acknowledges AMA as a community-based organization.