The difference between the Zuera and Braga chassis was not in the tube but in the front height. The standard Braga chassis sat a little higher than the standard Zuera. The difference in real time was minimal, certainly not more than two tenths of a second per lap in the hands of a first class pilot.
The different material on the CRG and Maranello chassis is indicated by a series of dots and dashes inside one of the front yolks.
I agree with the above in that a soft chassis didn't last longer than a few race meetings before they either broke or just bent so badly that it was pointless trying to straighten them as they bent right back to some useless settings in the front geometry. For that honeymoon period though, the soft chassis offered a lot more mechanical grip which obviously was an advantage if you knew where you could use it, not at every track or for a driver who didn't know how to manage his tyres.. The tyres were worked much harder.