All I know is, at the 60-70 foot level with tuned radials, it
really sings!

They do. I've always preferred an elevated vs ground mount
vertical. At that height on 80m, you appx equal to a ground
mount system with 60+ radials, if they are using 3 or 4.
Also, more clear of surroundings, etc.. Your local ground/space
wave will usually be better. I bet it's good to dx at 2-3 AM...
I've also used the usual L's and T's on 160m. Like Roy mentioned,
which is better will depend on the angle needed. The T is better
for strict DX, but often the L can be better to regional stuff.
I'd have to double check, but I don't think adding the other
half of the "T" top really changes the resonant freq a whole lot
vs the L. IE: when using a "T", you will still need nearly a full 1/4
wave from the base to either end of the top horizontal section
if not loaded.
What can be handy for low banders, is nearly any dipole can be
loaded up as a T vertical, if you short the conductors. Doesn't
matter what type of feedline. Loading a 80m dipole as a T on
160m, is usually far better than trying to load the dipole as a
dipole...
If you don't short the feed together, but only feed one conductor,
you then have a quicky L...Thats one quick way to compare them on
different signals to see which is best at a given time. 160 is kinda
weird...Often an L will outdo a T early in the evening, but usually
later,
the T will be better, even on the same short paths. Would seem to
indicate the higher angles are less used later at night..
Sometimes I run a 80 meter turnstyle, and feed that as a vertical with
an "X" capacity hat... That made a pretty good vertical which usually
beat
the L late at night. BTW, the vertical part of both antennas are appx
40-45 ft or so.. So fairly equal in that regard.
MK