StereoEnsemble is much humbler than Ensemble, its mono namesake.
Where Ensemble produces a dense and unreal texture like old string ensembles, what StereoEnsemble produces is much simpler. It’s just a stereo-scattered bunch of reinforcements, that you can spread using the top control and mix dry/wet with the bottom control.
It’s actually a half-decent simple room reverb, with its smattering of bright ‘early reflections’.
Use as you will.