Alan, I like your scans. I used to own a V550. It cost me new the equivalent of 200$. I thought it had an unbeatable price/performance ratio especially with medium format negatives, provided they were well exposed and developed correctly.
But then, if you think about it, actually even the line sensor in these cheap flatbeds is, in a way, a better scanning device than the interpolated sensors in mirrorless/DSLR cameras.
Just to clear up a few things. In essence, the raw output of Bayer-filter cameras consists of a so-called Bayer pattern image: an arrangement of colour filters on a square grid of photosensors. In the Bayer arrangement, this filter consists of a matrix of repeating 2x2 pixel patterns, one coding for red, one for blue, and two for green. Importantly, each pixel is filtered to record only one of three colors:
Bayer Filter
[source
https://en.wikipedia.org/wiki/Bayer_filter]
So the key thing here is that each pixel of the sensor is behind a colour filter and the output is an array of pixel values, each indicating a raw intensity for one of Red, Green or Blue. This arrangement needs an algorithm to estimate for each pixel the colour levels for all colour components, rather than a single component.
This is called `demosaicising'. There are different implementations of this - think of it as a type of signal interpolation. Now compared to the initial, raw intensity images, the reconstructed image is typically accurate in uniform-colored areas, but will have a loss of resolution (detail and sharpness) and edge artefacts. This is a big topic and one that is valid for the output of X-trans sensors too (perhaps even more valid as the output of an X-trans array has historically been found to be more difficult to demosaicise).
But to go back to scanning, most dedicated film scanners do not rely on Bayer (or equivalent) pattern matrices and the raw output they produce does not require demosaicing. The so-called `line CCD sensors' in a scanner are, at a very raw level, better than any camera sensor because they do not interpolate and because they use only a single line using the best part of a sharp dedicated lens so there is little or no optical distortion or other lens flaws added.
One consequence of the lack of a Bayer array+demosaicing is that when a scanner like the Coolscan 8000/9000ED or the Pacific Image is scanning 90mp, those are 90mp of full color data. Digital camera colour data is only 1/4 of the stated resolution due to the above. So even, say, a Fujifilm GFX 100 (a 102mp sensor, 10K$ camera) is only getting 25mp of full color data (and another 25mp of extra green [luminosity] data) from its 100mp of photosites. There are workarounds to limit that: eg pixel shift, but you are still left with the limitations of digital camera colour, lens flaws, having go through the hassle of stitching when scanning 120, plus any other issues inherent with the specific home-made scanning setup used (vibrations of the repro stand? imprecise sensor/film alignment? poor quality/evenness of the retro-illumination; and much more). Orange mask removal is another story and so is the lack of IR (infra-red channel) for dust removal in home made DSLR scanning rigs, but you know that already.
In any case - apologies to OP for further contributing to derailing this thread, which IMU wasn't about DSLR scanning at all.
. Same applies to flatness of field in the optics - at least to the standard I think is necessary.
