*Raises Hand*
I switched from a used Contax 645 / P30+ combo that I purchased in 2010 to an A7R in 2014, after passing through a Fuji phase with an X-Pro1 that ran from 2012-13.
Prior to the C645/P30+ combo (which I still have and use occasionally for daylight photography), I was using various m4/3 cameras, but upgraded to MF digital to achieve better image quality and potential sales sizzle. (I was told by several portfolio reviewers, gallery owners, and Mark Klett, who reviewed my portfolio with me when I was trying to enroll in one of his graduate classes at ASU, that if I wanted to be taken seriously, I would need to use a camera that had more presence than the diminutive Panasonic GF1 / GX1 I was using at the time. Klett had recently switched over to medium-format digital himself and he, in particular,
strongly encouraged me to do the same. Fortunately, I had the money and found some good deals on used gear, so I reluctantly made a major leap upmarket.)
What I didn't realize at first is that for the type of photography I do -- low-light, long-exposure, architectural-type photos taken at night (
https://audiidudii.aminus3.com/ if you're curious) -- getting enough DoF with a 44x33 sensor would ultimately prove to be very problematic, because stopping down the lens further also meant increasing the exposure length. (Although I did successfully adapt a few shift lenses to work with the C645 body, I needed tilt and swing to address my DoF issues and modifying gear to make that possible was beyond both my ability and resources back then.)
So what had been a 60-second exposure with an m4/3 camera would typically become a six-minute exposure with a P30+, which was long enough that I found it almost impossible to take photos without a car driving through the scene or an airplane flying past overhead or a person with a cell phone walking through it, etc.
Between test exposures to check focus and composition, combined with the need to cool the back for several minutes between shots to minimize noise -- especially during the summer months, where the ambient temps would often be over 100 degrees F at midnight! -- it sometimes took me an hour to take a single photo. Not only did this take a lot of fun out of photography for me, it also significantly reduced my yield, such that I sometimes returned home from an outing after taking only one or two photos instead of one or two
dozen photos.
Although the X-Pro1's IQ was a significant step down compared to the C645/P30+ combo, its smaller sensor was a welcome change, because the resulting increase in DoF from using shorter lenses allowed me to significantly shorten my exposures, which in turn made photography fun for me again, because I wasn't spending most of my time standing around.
Ultimately, the A7R, with its 24x36 sensor and strong performance in low-light, long-exposure situations, proved to be the sweet spot for me. And now that I have view-camera movements available again via a Cambo Actus and am median-blending multiple exposures to further reduce noise, I couldn't be happier where I've ended up.
That said, I found the A7RII to be a disappointment for my purposes, even before the star-eater issues surfaced. While it clearly offered a noticeable IQ improvement over the A7R for daylight photography, the one I worked with for three weeks proved to consistently create more chroma noise than my A7R when I used it for my nighttime photography. I was prepared to make the upgrade, but in the end, I realized it would actually be a
downgrade, so I skipped it and crossed my fingers that the A7RIII would prove better in this respect.
And perhaps it will, but so far, the fact that Sony is using the same sensor hasn't caused me to be very optimistic about its potential. I suppose I'll rent one in a couple of months to test it first-hand -- alas, I've found very few reviewers use cameras the way I do, so their comments aren't particularly relevant to me -- and if I'm wrong, then I'll eat my words and happily upgrade then. <shrugs>