Well ok to help stimulate the thread further !
….
I would say its not bull shine & having an overhang on the bottom rubber absolutely decreases the chances of a tangle.
I”ll use an extreme example to demonstrate…
Imagine your fishing with 2 float rubbers and you push them as close together as you can …so the top one as low as you can and the bottom one as high as you can on the float so there is little space between them...
You will create a pivot point between the two rubbers that the float can then twist round on itself on….same as if you tried to fish with just one float rubber say in the middle of the float. It will be able to pivot on itself and tangle on the line. If you now slide the two rubbers apart you lessen the chance to create a pivot point so you will have less chance of a tangle.
Therefore having your bottom float rubber pushed down as far as you can away from your top rubber will decrease the chance of the float twisting round on itself and therefore decrease the chance of a tangle.
I accept that if we are talking about a couple of millimeters with the bottom rubber either slightly up the stem or overhanging it will make a tiny difference but never the less - still a difference - .