Something completely different.

[tonyfoale]

Very interesting Tony!

The only thing I can wonder about is your using an aluminium tube to house your magnets. Did you want to use only the ends of the magnets? Because aluminium and magnetic flux repel one another. The ends of your composite magnet will see the greatest flux concentration. It may be the method behind your madness. Because you have done quite a lot of research in the rest of this design.

Aluminium is paramagnetic and relative movement of aluminium and a magnetic field will generate a repulsive force as you say but in this case there is no RELATIVE movement. The magnet and aluminium tube move together, I pointed this out in the video when talking about eddy currents.
Yes the ends of the magnet see the greatest flux concentration, that is what is required and I demonstrated that with my little screw driver test. If there were areas of concentration along its length a lack of linearity would ensue in the output signal, it would be position and velocity sensitive. I only want velocity sensitive.
There is no method in my madness, it just comes naturally.