In the ON4UN Lowband DXing book, the Inverted L is mentioned as being inferior to the “T Marconi” with flat top hat wires.
I can see why the Inverted L has some issues. When you have the combined horizontal and vertical parts of the wave, as ON4UN says you get the “sum vector” of the Vertical and Horizontal polarization. With a Marconi T style antenna, you get a classic lower angle, vertical pattern.
Since it only takes a relay to switch my new 17M EDZ from being a horizontal antenna to a Marconi T for the low bands, I will get it wired up and then do serious A-B tests. I’ll keep the default (power off) position to be the horizontal doublet and the power on to be the Marconi T.
Then I can test it on 160 and 80 against the Inverted L that I have.