Upload & Sell: On
There are plenty of savvy people who habitually shot at f16 on all larger MF formats. I never hesitated until after f16, the difference is very minor. Miniature format users get hung up on diffraction, whereas MF users are looking for the best trade-off between DOF and final sharpness for the intended use of the image and its processing path. Most MF images are/were very much made with quality in mind...
The 6x9 frame is a little short of advertised values (56mm x 82mm) and most preferred the 'perfect format' afforded by 6x7 (56mm x 68mm), esp with Mamiya 7 lenses, from memory the difference in real estate is 22% - not much, off a large base.
The big Fujis are rather clunky despite being manufactured seemingly from solid billet. The 690s' two button shutter sound is one of photography's greatest design flaws IMO, it sounds like a siege engine release. The Mamiya is smooth as silk in comparison. The Mamiyas are very much a MF look, all bite and solid detail, the 690s are very much a large format lens in an encasing body free of all modernity. Don't try setting ISO on one. Heavy too for a basic stone age tool, in either incarnation.
That shutter sound really bothers you doesn't it? Who cares? Especially if you aren't photographing people, which frankly I wouldn't imagine this camera would be that at anyway. It certainly is noisy, but one of photography's greatest design flaws? That's taking it to quite the extreme.
The rest of the points I certainly won't argue. It's basically a lens with a film holder on the back, but that's kind of what I like about it.
I also never really cared for the 6x7 format, it always felt like it didn't know what to be, it wanted to be rectangular, but it wanted to be square... I guess that could make you argue that it's perfect. I like the 6x9, despite the fact that it isn't quite literally 6X9.