While it may not be the popular answer, in my line of work we use industrial harnesses (made for transmission tower work) along with adjustable anchor straps. Release is by means of seatbelt cutters mounted and easily accessible on each harness, that (tested) slice through the anchor strap(s) instantly.
I have no trust in the dial-a-death chest-mounted quick release knobs when doing photography work, as equipment is frequently pressed against the chest and other items that could agitate it. Same goes for quick-release buckles in the back. The cutters are accessible with either hand and only require one hand. I am in in agreement that fall-arrest type straps have no place in an aircraft.
As far as the photographer being restrained primarily by a seatbelt, that simply doesn't work for a lot of missions. The flexibility isn't there.
One other important point is that the camera equipment should never be anchored to the harness or the photographer directly, but rather to the aircraft, lest the cameras act as an anchor should an evacuation be needed.