Peter,
I agree fermions are probably more complex than a spherical shell, I keep getting pointed towards tori, with only 'handing' of view dictating whether we find an electron or positron (see Majorana..)
The interesting thing is they do couple with light (absorption/re-emission) but have a refractive index on 1. i.e. they leave no EM 'signature' (except kinetic when in motion, which we do find) so are 'dark'. They also have the right mass for dark matter, populate the outer halos of galaxies, and indeed form the surface fine structure of ALL matter! I've never seen anyone argument against them or even consideration of them!
The 'discrete field' model I developed suddenly seemed able to produce and resolve a whole tranche, indeed just about every anomaly is astrophysics! I got a paper published, though the top mainstream journals ran a mile as it was 'new physics'! Perhaps you could have a look and see if you can find any inconsistencies; HJ; A Cyclic model of Galaxy Evolution, with Bars
I see I haven't rated your essay yet so will do. Hold on for take off. Mine's been hit with 11 '1's so far so so I hope you'll think it's work a good one too. Do revert on my string with comments including on the above paper.
Very best.
Peter