"The bass recorder is a standard instrument for recorder quartets and recorder ensembles. It’s not possible to replace it with the Great Bass recorder. " - andreas1
This is not true. The "Great Bass" is the name used for two different recorders, the quart bass in C and the contrabass in F. The C instrument range is from C in the bass clef to approx. D in the treble, the contrabass is from F in the bass clef to approx. G in the treble. The so-called "bass" is an octave higher than the contrabass. Both "great bass" ranges overlap with the tenor recorder, so either could easily be used for bass parts. In fact the Great Bass will give a lower tessitura while still covering the middle bass notes as well as a richer tone which is probably why it is used in this ensemble.