Here's a shot where I finally got my sh!t together, and captured a decent image of the model - 16 bit RAW file. Files show as approx 208MB on the SSD card. Buy bigger cards!
63mm f/2.8 at 1/100
This is the sort of image I'd typically work on for publication, so I went ahead and processed this as I normally would.
The shot is imported into ACR and I apply the Mastin Labs Portra film profile, and adjusted WB and exposure to suit.
I had to reduce magenta on this AWB image - Maybe a pattern here?
Loading into ACR takes longer than a 50MP file, and it takes ACR longer to render an image to work on. Not a crazy difference, but noticeable.
I then open the file in Photoshop. Photoshop seems to cope fine with a single open file. It shows as a 517.17MB 16 bit image.
I'm using a MacBook Pro - 2.8 GHz Intel Core i7 - 16 GB 1600 MHz DDR3 - Intel Iris Pro 1536 MB - 1TB SSD
When I open the file it gets my fans spinning for a few seconds. When I zoom into the image it takes a second to render the full detail.
Scrolling, editing, spot removal, adjustments all appear to work as with the 50MB files.
I find the image a little cool, so load NIK ColorFX Pro to apply a Skylight Filter.
Now this is much slower than before - as the PS file is ported to NIK, and rendered, it takes a while, and the fans are definitely ramping up.
I apply the filter, and tweak it - the export back to PS - this again takes noticeably longer than with a 50MB file.
Next I drop the image into Portrait Pro for retouching. Takes longer than the 50MB file again, loads ok, and the AI software finds the facial features really well. I have noticed that Portrait pro likes more pixels to work with, and makes better decisions with bigger files. This appears to pan out for the 100MB files.
I apply my standard starting profile, map the skin area on the face carefully, and clean the areas and the lips and eye makeup. I can then see how my standard skin smoothing looks.
It looks good - skin is cleaner, bags under the eyes are less, crow's feet are reduced. I do some manual touchup on blemishes and stubborn crow's feet. This appears to all work the same as with the 50MB files.
Brighten the iris a touch, clean up the whites of the eyes, and make the pupils fractionally bigger.
I didn't apply any facial geometry tweaks to this shot.
Finally add back in a hint of magenta to the skin tone only, and export back to PS.
This again takes quite a while - this would definitely impact workflow for medium to large scale image retouching.
Back in PS, everything looks good - final zoom in and spot removal before saving the PS file and then a full res JPEG.

Observations:
Bigger files = slower workflow (duh!)
For portraits the level of detail is going to require retouching, depending on your required output standards. You can mitigate this with makeup, lighting etc, but you will have to have a workflow to deal with it.
All my current apps worked ok - rendering the final image from Portrait Pro to PS caused horizontal lines to temporarily appear across the image, but these were not there in the final PS file.
Final IQ looks excellent - a typical US print magazine page requires 3,300 pixels on the long side for a full bleed image - this file is 11,421 pixels on the long side.
Note - ACR is not importing the images as native 4:3 which is odd - Each RAW file renders in ACR as 3:2 cropped, even though it's a RAW only file, not a RAW + JPEG with in camera crop. Import size is 7,768 x 11,421 pixels. Maybe someone left the camera in 3:2 and I failed to notice (quite likely).
Too early to tell if AWB is better/different, although I did have to adjust Magenta down as with 50MP files.
None of my RNI film profiles showed up in ACR when working on this file - so it didn't appear that this file was recognized as a Fuji file they could be applied to. Another issue that would hopefully be fixed with an ACR update.
Uploading to the cloud took longer, but I was able to use the full res JPEG file from Flickr and insert it into this post with no issues.
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Your time is limited, so don't waste it arguing about camera features - go out and capture memories - Oh, and size does matter - shoot MF