I said the sound of the older 5-screw model has slightly more “harmonics” or overtones. That is a loose way of saying the tone was a bit fuller or richer. As I sit here now switching back and forth between the 3-screw and 5-screw models, I hear a slight difference in tone between the two, but the difference varies in funny ways depending upon if I am playing high notes, low notes, intervals, or chords. And when do I hear a difference, I am not sure which one I like the best.
So I don’t think it matters which one you buy or play. They are pretty close in tone. Generally speaking, the 5-screws seems to move air faster, be slightly louder and generality fuller. But again the difference is very very small. For most uses, I would buy either without consideration for the differences.
The 5-screw is older and a bit heavier, and it feels like you are picking up a small log. That could add to the coolness factor.