That is all true, Craig, but it is more relevant for DSO than planetary and solar imaging. For solar system stuff smaller pixel size is more important.
You might find this thread interseting. In particular check out the image that Dennis has posted. For planetary (and solar and luna) imaging, the longer your telescope the smalller the pixel size, within reason. With DSO you are looking for a resolution of around 2 arcsec/pixel as an average, planetary you go for 0.5 and smaller (assuming the seeing will allow it).