That's certainly not true at my QTH. The vertical has two
extra S-units of noise on receive compared to my dipole.
I'm assuming the two extra S-units of noise on receive
won't affect my transmitted signal. When I had my 40m
vertical up, I never heard any signal that was better
received on the vertical. +12 dB of noise is virtually
impossible to overcome in actual practice.

If you get two extra units of noise, but the signal comes up
four.... Well, you get it... I didn't get much extra noise going
vertical at this location. The stronger signals always overrode
it. The noise should be a non issue in most cases.
But this also leads to an important question. Do you actually
work long haul paths? If you don't , you probably won't see
much advantage to a vertical. If you listened to long haul dx
paths, and the vertical never beat the dipole, you didn't have
a very good vertical. Actually, I've already pondered on that
in the past. Yours was pretty low, with not many radials
the last time around. The combo of mediocre antenna, and
not using it for long paths is why yours was never better
than the dipole. If I remember right, you weren't even talking
over 1000 miles most times.

But almost all my GP's
had the radials attached to the mounting plate, which in
turn was mounted to the mast.

Conductive mast?

Sure. Grounded at the base too.
MK