The video above is my rendition of Bach's Sinfonia from Cantata BWV 156 "Arioso". There are many transcriptions of this work available online for organ, but from my experience many of them haven't been satisfying. Nevertheless, I did stumble across this arrangement whilst browsing the internet! It's an arrangement by A. W. Morse who also is a Hauptwerk fanatic. Have a browse through his site—there is plenty of interesting Hauptwerk related things!
I hope you enjoy my rendition of this piece. I use the Velesovo sample set from Sonus Paradisi. On the repeat of the first section, I add the tremulant to the solo voice and extra ornamentation.