I dont mean to sound like a prick but to me it seems to be reading a bit too far into things.
How is rating a rod by thickness of line (PE) any different than rating it to 80lb braid, braids BS fluctuates so wickedly the numbers can only be used as a guide anyway.
I personally like the idea of round about figures in the rating of rods, as not to try to absolutely categorize a rod type. I can still use an 80lb rod for 60lb line and enjoy it, and visa versa.
Most jigging with braid or PE line is knock down fishing anyway. measuring drag spikes is an interesting thing to do on a rainy day. Its amazing to see how big of a drag spike you can produce with a 9kg drag setting when theres no give (stretch) in the line.
If I have the normal drag range a rod can work with, the maximum dead lift, the recommended jig weight, the rough line rating, the length, plus the action, for me its definatly enough to get an idea of what the rod can be used for and how far it can be pushed.
Personally, I like safety margins, I still bump the rod on the rail from time to time when loaded up, and if the rod was always being used at 100% capability im sure we would hear of alot more gear failure due to operator error.
As for your original question, if a rod is rated PE3-6, if your an optimist treat it as 30-60 and if you like to take a chance, treat it as 40-80.
Cheers
Ben