Point is Marc, of all the things you list, only dust motes on filters makes a difference to the original question - whether to do a different one for each filter. The rest of the aberrations etc. you list are dealt with via any flat (which definitely IS essential).
I now typically use a TS filter slider, for various reasons, and so I can't guarantee that the dust motes don't move unless I take my whole filter series in one run (which I sometimes do, most often don't). So in that case, it makes no sense for me personally to do separate flats for each filter. However, I do make sure I give the filter a quick, fresh burst from my air-bulb before I replace it each time! All about compromises...
