Bach Motets: Evidence for Performing Unaccompanied

I'm considering performing a Bach Motet next year. One of the considerations for performing one of the Bach motets is whether to use accompaniment. There has been significant scholarly disagreement over the matter, and I'm wondering what recent research there is on the subject. I found this today on a website by Thomas Braatz. I'm posting it here for future reference and for your elucidation.

Indeed, the parts for "Jesu meine Freude" are not by Bach. Moreover, recent research has determined:

1) the singing of Bach's motets a cappella is not a romantic-style innovation of a later period than Bach, but rather can be documented as the manner of performance of some of these motets (a carrying on of the tradition that was already established under Bach?) under the cantorship of Johann Friedrich Doles who conducted/performed these motets in this fashion at St. Thomas Church from 1756 to 1789.

2) new evidence that some of Bach's motets, such as this one, were very likely performed a cappella without colla parte instrumental accompaniment or bc

In Klaus Hofmann's new book, "Johann Sebastian Bach: Die Motetten" [Bärenreiter, 2003] pp. 55 ff., the following evidence is presented:

1. in 1761 and in 1764, the music catalogs of printed works available from the publisher Breitkopf in Leipzig offered copies of Bach's motets in the category "Motets - without instruments"

2. the music theoretician, Johann Adoph Scheibe (1708-1776) (his father, Johann Scheibe, an organ builder was very highly regarded by Bach) is the infamous critic of Bach's music in the Birnbaum-Scheibe controversy. To consider his attitude toward Bach to be entirely critical would be unfair since he was also one of the very first to praise in print Bach's 'Italian Concerto.' Scheibe was encouraged by Telemann to publish a periodical, "Der Critische Musicus" ("The critical Musician"). From a reprint of an issue of this periodical dating from 1737 [Hamburg - he had just recently moved from Leipzig (where he had had most of his schooling including some time at the University of Leipzig, until his father's organ building firm went bankrupt)] but reprinted in Leipzig in 1745(facsimile Hildesheim, Wiesbaden, 1970) pp. 181 ff., Scheibe comments on the actual motet performance practices he had experienced in Leipzig:
>>Der Generalbaß sollte zwar allezeit dabey sein; allein, man kann ihn selten gebrauchen, weil die meisten Motetten nur von einem Chore Sänger aufgeführet werden, es müßten denn andere Instrumente mehr dabey seyn, oder man müßte sie bey gewissen Gelegenheiten in der Kirche aufführen.<<

Klaus Hofmann interprets this passage to read: "In reality, a basso continuo ought to be part of this ensemble, but the general performance practice/tradition rarely makes use of this option, because most motets are performed only with voices. It is, however, an entirely different matter if more instruments (beyond the colla parte and bc accompaniment) are used, or when the motets are performed in the church on very special occasions." Klaus Hofmann also extrapolates from this passage the fact that a cappella performances must have been common practice under Bach's tenure in the 1730s.

3. there is no record of any original instrumental parts for "Jesu meine Freude" as ever having existed at any point during Bach's lifetime.

Johann Adolph Scheibe, who participated in the singing of motets under Bach's direction (1723), listened carefully and experienced the exhilarating joy of performing these works as a 15-yr. old student stated later in the reference given above (pp. 179 ff.): "Eine geistliche Moetette, wenn sie in ihrer völligen Stärke genommen wird, verursachet eine außerordentliche Fröhlichkeit des Herzens; sie machet uns munter und doch bedachtsam; sie erhebet das Gemüthe zur Betrachtung." ["A sacred motet, when performed at full strength in numbers (not OVPP but at least 3 or 4 per part), creates an extraordinary joyfulness in our hearts, it awakens us while, at the same time makes us move forward cautiously; it uplifts our spirits to become {more} contemplative."]