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I should have made it more clear that I was refering to the imaging case.
I agree with Mark (and that other S&T piece) in that for visual observing larger aperture wins every time.
For imaging, the isoplanic wave (ie block of air that is stable across the aperture of your telescope) needs to be larger to appear stable in larger apertures....but the rub is, the refractive index changes for these waves are often directly proportional to their wavelength.
Smaller apertures as a result often have a more optimum (ie smaller) refractive index changes.
What is intestesting is that high speed tip-tilt optics did not exist for amateurs back in 1971, and (without trying to sound like an advert) these can and do correct slow seeing changes that were impossible to compensate with film based systems.
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