Ein feste Burg ist unser Gott, KrebsWV 518

Another tribute to the day, this Trio on "Ein feste Burg ist unser Gott".
According to the manuscript I transcribed it from, it was written by Johann Ludwig Krebs. It even has a KrebsWV-number, so apparently scholars too think it was composed by Krebs. Yet somehow I have my doubts about the authorship of Krebs. It certainly is a charming piece, yet the harmonies are clumsy here and there and the voice leading is not very expertly done. In other pieces I know of Krebs he shows himself to be a far better composer than one would suspect based on this piece. If it really is a piece by Krebs, it's probably a work from his younger years.

Score available here: http://partitura.org/index.php/johann-ludwig-krebs-ein-feste-burg-ist-unser-gott-krebswv-518/