After trying many verticals, today I work with what for me is the best vertical for 11 meters. The performance far exceeds 5/8. Best of all, the absence of QRM.
I compare the DL-40 with a Double Bazooka dipole and always better
DX stations "fall" with an impressive ease, most stations ask about the type of antenna.
From the first day I tried it, I was amazed, at first I thought I had put it wrong, there was nothing of QRM.
What a GUN antenna! When I do DX to North America they are very surprised that I answer them, when they are in minimal working conditions (100 W. and a wire dipole).
The antenna is a gun, compared to another multiband Yagi optimized with many more elements, always superior.
In UHF works much better than the Diamond X-200 and that BiQuad is 1 meter lower.
Very good antenna, good quality materials, 5 bands ... I recommend it!