just to add to aris description of rolleiflex FX screens ...
the normal screen that comes with FX is indeed much better than any older ones, but not as good as the hasselblad ones. the high-D-screen (the one from 6008integral and same as 6008auto and hy6/afi) is a significantly better one - brigher and finer/smoother in texture (though not quite as smooth as specially dedicated super-smooth groundless). the snappy focusing is especially remarkable in indoors with lower light available.