What is the advantage or dissadvantage of having Tween 20 in flow cytometry wash and staining buffers?

Tween-20 is a detergent used to permeabilize cells. It is a non-selective detergent that can extract both proteins and lipids and can permeabilize all lipid bilayers including the nuclear membrane. Saponin is another commonly used detergent, but mainly solubilizes cholesterol, leaving protein surface antigens intact, and cannot permeabilize the nuclear membrane. The action of saponins is also reversible as the saponins can wash out. It is more advantageous to use Tween-20 if staining the nucleus, but saponin may be a better option if staining the cell surface.