Well, at last I get around to putting my Imagon opinions down! Never been so busy and short of time as since I have been retired?????
Back in the day I often used the Zeiss Softars with their little pimples that formed separate overlapping images in the frame and rendering a glow in hightlights. Particularly with 3/4 backlight or rim lighting. It was said at the time that the Softars gave an Imagon effect.
Year later, when I had an Imagon in the hope of an outcome similar or even better. Close, perhaps, but really no cigar.
As I've said, I also had a Kodak Commercial portrait lens which proved immensely informative. It did not have the kitchen collander aperture discs and so when working with the Imagon I left off the aperture disks, essentially using the lens wide open with the image formed by the entire optic and not just the localised sweet spot.
Those sieves can do funny things to highlights which I am not sure that I am all that enamoured of. Left on its own, the Imagon renders a lovely look which smacks of being somewhat 'vintage' which I like. (Although, not as much as the Kodak albeit the Kodak was used on 8x10 and the Imagon was on 4x5).
I mention this because when it comes to 'soft focus' I feel that the results are enhanced by the enhanced smoothness of tonal rendering afforded by image real estate.
I not only envy you your 8x10, Maris, and your Imagon, I also evy the ability, these days, of lugging such kit and functioning. Walking sticks and vertigo are not ideal bedfellows to such endeavours.
"We see things not as they are. We see them as we are."
— Emanuel Kant