FLA004 Bach double violin concerto~
Arguably the most difficult of these pieces, Ian Wilson's re-working of BWV 1043 for four recorders (strictly speaking six, since soprano and tenor players have also to play alto at some points!) is surprisingly successful, and will prove a challenge and a delight to advanced quartets.
Sample page~~Score and parts|FLA004.2|Score|FLA004.1|~4347~4366~~