The manual that came with my 8500 (not 8500W) says "You may program up to 12 Security+2.0 remote controls, 2 Security+2.0 keyless entries and a combination of 16 MyQ accessories to the MyQ control panel."
Be aware that the MyQ control panel is the 888LM control panel that seems to fail after about 4 years - see the thread "LM8500 Wall Controller Failure."
