i have a rigid back, it is definitely very restrictive but cables or chains keep my father too insecure. with chains i imagine it but painful if you sit longer, because the pressure is not evenly distributed.
since I have only a small hole in the back to "crap", I have to be very careful that the hole over my hole sits correctly otherwise I have big problems.
it was difficult in the beginning and my father often had to unlock me to clean, but he insisted that I learn it and now it works well