Another aspect that hasn't been mentioned yet is the impact of microlenses. KAF-8300 stars are pretty easy to pick once you're familiar with the "look." I have been unfairly accused of adding diffraction spikes to stars in refractor images taken with a KAF-8300! As well as an effect on star shape I believe they are responsible for an amount of bloat as well, presumably through scattering some of the incident light.
I don't know enough about sensor technology to be sure but it seems very likely that small pixels have a lower fill factor and place greater demands on physically smaller microlenses. I'll have to finish reading some of those big, fat books on CCD technology sitting on my bookshelf
Cheers,
Rick.