JibONE's carrying capacity is 11 lb (5 kg). HeadPLUS PRO by itself weighs approximately 9 lb (4 kg), so, there will be 2.2 lb (1 kg) left for the camera's carrying capacity overall. HeadPLUS PRO's carrying capacity would not be used fully which is why we do not recommend this setup.
However, as long as you stay within 11 lb (5 kg) carrying capacity, using HeadPLUS PRO with the JibONE will be within your own risk. There are enough counterweights to carry 11 lb (5 kg) of load included within the JibONE. These specifications are given for while using JibONE's arms are fully extended. You may also shorten the arms of JibONE to make the system to support your HeadPLUS PRO as well.