Regarding the J. S. Bach and the overall nature of early 18th century
temperaments which he might have used, it is most instructive to read
further in Lindley's
article in Grove's:

7. EQUAL TEMPERAMENT FROM 1735. In his Generation harmonique (1737)
Rameau endorsed equal temperament and, by way of retracting his own
views of 11 years before, introduced a new argument in its favour:

He who believes that the different impressions which he receives from
the differences caused in each transposed mode by the temperament [now]
in use heighten its character and draw greater variety from it, will
permit me to tell him that he is mistaken. The sense of variety arises
from the intertwining of the keys [I'entrelacerment des Modes] and not
at all from the alteration of the intervals, which can only displease
the ear and consequently distract it from its functions.

Distracting the musical ear from its proper functions is an unpardonable
fault in a tuning. Rameau's argument might well have applied more
palpably in France than in Germany, if French unequal tunings were, as
they generally appear to have been, less subtle than their German counterparts.

[end of quote]

So if French unequal tunings at the beginning of the 18th century were
less subtle than the German, where does that put German tunings?
Certainly not in Joseph's supposed near-meantone zone, about as unsubtle
as one can get.

Note that Lindley divides his article up into blocks of time and
temperament types, jumping from type to type, so the above section head
should not be intepreted as meaning ET only emerges around 1735.

On Bach:

No unequivocal conclusion can be established as to the attitude of his
father, J. S. Bach, towards the relative merits of equal temperament and
a mildly unequal one. On the basis of evidence such as applied above to
C. P. E. Bach, Barbour showed (1932) that J. S. Bach would probably not
have held a dogmatic opinion. Barbour's later statement (1951, p.l96)
that 'much of Bach's organ music would have been dreadfully dissonant in
any sort of tuning except equal temperament' is an exaggeration (due
perhaps to the fact, which he mentioned in a letter of 1948 to A. R.
McClure, that Barbour had never heard any keyboard temperament other
than equal temperament). During the 1960s John Barnes investigated the
'48' in a fairly subtle type of 18th-century irregular temperament and
found that the peculiarities of the various keys in that tuning were
nicely suited to or accommodated by the music. According to Marpurg
(1776), Kirnberger scrupulously reported that Bach, his teacher, had
instructed him to tune all major 3rds larger than pure - thus ruling out
any unsubtle irregular temperament (such as used by Kirnberger himself).
One could readily believe that Bach sometimes exploited the qualities of
a particular key as inflected in a typical irregular temperament,
sometimes merely accommodated what he knew was likely to be the kind of
tuning his published music would be played on, and sometimes - for
instance, in the concluding ricercar of the Musical Offering - ignored
completely the possibility of intonational shadings.

[end of quote]

So for Lindley, the question seems to be whether or not Bach preferred
equal or mildly unequal.

Lindley also quotes Fontanelle, who had written in 1711[!] on the
advantages of equal:

After these motley combats, one system will become victorious. If
fortune favours the best system, music will gain thereby a real
advantage; and in any case it will at least profit from the convenience
of having the same ideas and the same language accepted everywhere.

[end of quote]

Note the date. If these "combats" were already well underway in 1711,
how long had they been going on?

I have offered my own supposition that musicians devised their own
temperaments based on the needs of the literature they encountered, and
that written documentation is most likely after the fact. This is exactly
the situation indicated by Marpurg (1776):

There is only one kind of equal temperament but countless possible types
of unequal temperament. Thus the latter opens up to speculative
musicians an unstinting source of modifications, and since every
musician will readily invent one, the result will be that from time to
time we shall be presented with a new type of unequal temperament, and
everyone will declare his own the best.

[end of quote]

Late, yes, but it is the practice of each musician finding his own
solution that I wish to point out.

Joseph's problem is what we might call Chronic Revolutionary Syndrome.
He and I are both old enough to remember when we had to fight against
the then prevailing idea that Bach wrote the WTC to show how great ET
was. It is common for revolutionaries to swing too far in the opposing
direction, which may in fact be necessary initially to begin tipping the
balance. But the danger is always that of going too far, so far that you
keep on going into extremism in the other direction. This seems to be
Joseph's current position. He would have us believe that not only did
Bach NOT advocate ET, but (at least early on) he was a old-fashioned
conservative, ignoring the general trends of his time and sticking to
the temperaments of earlier centuries, an anachronistic hold-over
unaware of the debates ragging around him. This may produce
"interesting" sounding recordings, but does nothing to help correct the
situation. Actually, considering the degree of audible distance of both
near meantone temps and equal in comparison to more historically
plausible "Bach" temperaments (i.e., Valotti- or Neidhardt-like well
temperaments), I would posit that Joseph's use of the former is a
greater falsification of the original sound of this music than
performances/recordings which make use of equal temperament. Musicians
themselves are also somewhat to blame for this skewed idea of historical
intonation: many harpsichordists are unaware of all but the most basic
well temperaments, such as Kirnberger and Werkmeister, and these
easy-to-set though unsophisticated systems find a current frequency of
usage which probably has little historical basis, again creating a false
impression of the severity of the harmonies in much of the music in Bach.

Hopefully the pendulum will eventually swing back again until it comes
to rest at the middle point suggested by the cool-headed scholarly work
of Lindley and others. But until those who offer their professional
services as producers/technicians of "historically informed" recordings
actually become "historically informed" themselves, we are no better off
than we were in the 1950's in this respect.

PP

PS Because of space, I have left reams and reams of info out in this
selection of quotes from Lindley. I recommend the article to everyone.

For anyone who wants to try them, I can give you the cents deviation
from equal for various Neidhardt and Sorge temperaments for tuning by
machine. If you want to set them by ear, I can give you the comma
division logic, and you'll have to work out your own beat rates/tuning sequence.