Oy Vey, my head hurts after reading all this, and it is spinning,
spinning, and the blood in my veins is transforming into chili...
Maybe that is why I have converted my balanced antennas to 600 ohm feed
and built my own link coupled, balanced tuners... Because chillun' if
youse look at the so called balanced tuners everyone is peddling these
days, dey haint... hey, I read Huck Finn when I was a kid, also

So, let us summarize...
I suspect that most will agree that using a B A L U N to coaxial feed
an unbalanced load, such as a Zepp, or a ground mounted vertical, is
not a good idea...
I suspect that most will agree that that using a B A L U N to coaxial
feed a mostly balanced load, i.e. dipoles, inverted vees, yagi-uda's,
etc. can be a good idea - depending...
Where I suspect the water gets muddy is when we carelessly
intellectually speaking mix the functions of a choke balun with an
impedence transformer...

As Roy has pointed out, having both magnetic activities on the same
core will allow mixing of the core flux and possibly probably even
degrade the functioning of one or both... Notice that Sevik has
designs that use two or more cores to separate the functions of
transforming impedence and of choking common mode current.. And that he
has no hesitation in series connecting two or more devices to get to
the final result desired...

Probably, the cleanest way to doing both a transformation of impedence
and of balance is to use one or more UNUN's in series to reach the
desired impedence, and then series a 1:1 BALUN designed for that
impedence level... If you still lie awake at night worrying about
current on your feedline, the add a solenoid wound, coaxial choke below
the whole mess...
Or go back to wire feed...

denny / k8do