thanks to the posts here, we finally start getting a better understanding of what's going on. i have given a lot of thought on this, so here is another idea (pentax engineers around?):
i still think lowell's idea is the greatest-end-all solution, _but_, i still believe the precision requirements involved in implementing it are virtually prohibitive (i believe this is why pentax changed the operation of the paerture lever when moving from m to a). so _if_ this is indeed not doable, how about a compromise: give me an option to set the aperture with the back wheel, as i tend to shoot in aperture prio anyway, it would work for _me_, and i don't even have to be spot on with it (if i miss the mark by one stop or so it's no big deal, i would still get a decent reading, not 2 stops off, as it is now). this means i would have to set the aperture both on the lens and on the body, so it is a bit annoying, but it would be a decent workaround, and would enable the body to apply the required curve for adjusting the exposure.
another nice thing, seeing as we have a body with interchangeable focusing screens, would be to be able to customize that response curve for the metering, depending on the screen used. how about that?
(it is a different issue, though)