I see this first hand, very obvious and pronounced disc structure.... I sample at 0.44" with a 12.5" @f/8. When I run focus routines I can see the airy disc itself with the bright core where most of the energy resides and the outer rings. Sampling at this level tends to really clearly show issues such as tube currents etc. With smaller wells, the washy airy disc can quickly register a sizeable portion of the available dynamic range. It seems to further amplify the effects of the CCD micro-lens. The washy disc causes a "shimmer" over the lensing, very tiny diffraction spikes which further spread from the disc structure. - I have watched this live at 100+ fps using another sensor with similar sized pixels to my main 8300 sensor.
There are some cool advantages - I have revealed some pretty tiny structures within some targets but bright point sources of light tend to suffer greatly, i.e stars themselves and I am yet to find a way to suppress it. You can do short subs, but other parts of the target will suffer.
Oversampling excessively also results in significant loss of sensitivity and any forms of aberration present, either optical or environmental become extremely obvious.
A few examples:
Oversampling with long subs:
Antennae Galaxies, core structure
Shorter sub composition for High dynamic range targets:
Core of the Sombrero (note the strange diffraction spikes.... thats a @!#$ spider building a web in my OTA that i didn't discover until the following morning)
It's a nice thing to have data present that would otherwise not be seen when sampling less, but I find 80% of my time is dealing with the adverse effects. Bigger camera should be here soon so I'll be looking forward to less fuzzballs...