I have made some comments to this thread, but now I am thinking of a holiday in October last year (yes I did manage a break despite the pandemic) ?
I had taken a few rods (3) and several reels / lines. The cottage we stayed in had a field attached, so I could try out my rod/line combinations ? All in the ATFM 3 or 4 range. I had lines from Orvis, Maxcatch (Gold and standard) and Hardy/Greys. I tried them on a Greys Streamflex 10' wt4 an Orvis Frequent Flyer 9' in wt4 and a Maxcatch 11' wt3. It was "interesting" The only rod that could use all the lines was the Maxcatch ??? The best line was the Maxcatch Gold, followed by the "Standard".
Now this is based on the ATFM rating and "My" abilities. I did put a 5wt line through all three rods and they all coped, but for distance and presentation the Gold was the best all rounder, with the "Standard" only marginally less. I found the Orvis line died as the power increased, all lines worked well at short range, but the Hardy/Greys lost accuracy with distance. I had hoops set up at 5m, 10m and 20m. I also had a straight cast area to compare distance.
Who would have thought that manufactures claimed did not match up with their products ? But cheap Chinese "copies" did better ?
Since this test I have tried my other rods. The only rod that beats all others in a range is a Greys Streamflex 6'6" (MK1) 3wt, but with a 4wt Maxcatch standard line (I have 6 similar rods in this range). This is my go to small river rod.
My tests prove to me that the ATFM rating system is a "Guide" only, nothing beats actually trying a set up. There are too many variables to feed in, not least an individuals ability !