'Ein feste Burg ist unser Gott' (BWV 720)

Registration:
Hoofdwerk: Octaav 8′
Rugwerk: Roerfluit 8′, Octaav 4′, Fagot 16′
Bovenpositief: Praestant 8′, Quinta 3′
Borstwerk: Fluitgedekt 8′, Praestant 4′, Sexquialtera
Pedaal: Subbas 16′, Holpijp 8′, Trompet 8′
Hoofdwerk+Bovenpositief, Hoofdwerk+Borstwerk

Modern editions suggest this piece should be played on 3 manuals. However, there are also manuscripts which indicate 2 manuals. And in my opinion, this is much more logical and consistent, because in the score itself, there are only indications for Fagotto and Sesquialter and for Oberwerk and Rückpositiv. I think these indications correspond to each other: Fagotto = Oberwerk and Sesquialter = Rückpositiv.

If you want to use 3 manuals, you have to alter these indications. So modern editions add Brustwerk indications, suggesting the Sesquialter belongs there. I just don't buy it.

Still, I do use the Borstwerk Sexquialtera in this recording, because in Zwolle the Fagot is on the Rugwerk. So I cannot use the Rugwerk Sexquialtera.