* 280EZRider, but I've worked on dozens of really skunky brake hydraulic systems, which have never been fluid-changed, and there's not been any swollen rubber. A certain amount of sludge but no deformed rubber.
* During a fluid change/flush, the master cylinder piston travels the full length of the cylinder and, if there's rubber damage, the pistons won't return properly. Of course this necessitates a new master cylinder and a good flush (which is totally warranted given the absence of maintenance) but I still wonder what is working on the rubber, since not all the unmaintained hydraulic systems fail for this reason (whatever it is).