the biggest issue is the 80-10 EFHW has a terrible pattern, broadside at 80m and by 20M
its a 4 lobe pattern with 10m its practically endfire.
That creates issues and questions for comparison as the EFHW is then rarely aimed at
the receiving station and hence you do not have a known comparison.
Generally when testing loops a loop of known performance are used but testing at HF is
never easy as the near field is at least 5 to 10 wavelengths or more and ground quality
dependent. You want that distance to be able to see the total field. The easiest rig
for that kind of testing is two fiberglass boats on calm salt water (an almost near
perfect ground plane). Of course that does not include RF sources and calibrated
receivers and accurate GPS.