This movement (with the most da capos ever by Vierne) seems to me like a quite sunny island in the context of the very dark and depressive Symphony No. 4.
For this recording I've coupled the 8' Flûte of the Bombarde to the Pos with the Hauptwerk internal couplers, because the Bourdon 8' of this sample's Pos. cannot replace a Flûte 8' which is intended by the Composer. So it's become more Notre-Dame than Rouen ;-)