I cannot see why even the cheapest fluid would make any difference to the pedal feel. All these fluids are basically similar and do not compress. When they get hotter than their rating I can see they could cause problems, but in normal driving that will not occur.
These cars have soft feeling pedals, I went down that road, I think the master cylinder is too small in diameter and feeding brake lines that are also too small, both should be a little big larger. I added SS lines and I do not think it made much, if any, difference at all.
I think that the bores of the rigid lines attached to the frame are smaller than the bores of the flexible lines going from the frame to the brake cylinders and that causes problems.

 

You are probably right, and I'm too lazy to change mine again anyway as long as they continue working. ( and they do )

 

changing to the higher temp resistant fluid, and metal lines is for heat build up under high performance conditions. Brake fluid is brake fluid under normal operating conditions. It shouldn't make any difference in pedal feel. I think many are still running 10 yr old or better fluid. and over the years it breaks down and gets contaminated. I didn't completely change the fluid in our little N/A we are working on, and it seems to be fine. If it bleeds off again, it might be time for a complete drain. Trying to save the guy some money.