I actually think the maximum speeds for the various EMD gear ratios were originally about 5 mph slower. They raised slightly as armature bonding methods improved.

The 79 mph limit makes sense. The ICC/STB/CFR limits passenger trains in signalled territory to 79 mph unless some sort of CCS or ATS is functioning. I know SP had ATS for a while on Donner, but I'm not sure there are too many places you would want to do 79 mph without a parachute.

I don't mind running 24RL brake, I just hate the thought of having to work on it. The biggest problem with any 24 is figuring out what version you have, if it really has pressure maintaining and in what position. SP changed first service to pressure maintaining, but I've also ran one of the later versions that still had first service and pressure maintained in lap. It's been too long since I ran 14EL, so I would probably throw myself through the window with the independent until I got used to it again. 6BL is a good brake, but you can't beat 26L to run or rebuild. I hate the desktops and electronic brakes.

Don't worry - when RCU, PTC and Digital brakes are fully implemented there will never be another accident (that they won't be able to blame on an employee).