Let's bring some thoughts together ...

Compression is slightly less than 1/2, such as from 15mb to about 8mb.

You also might be able to get a faster flash memory. 

While smaller file size will write to the cards faster to the camera's
memory buffer Martin,  this does not mean the camera will be able
to capture more shots by speeding up the frame rate

All other things being equal (unless I'm missing something), smaller file size
must mean faster possible frame rate. 

You see, large file sizes are nice to have in working an image for print. 

Yes ... ... with a jpg file, larger file size means either more pixels or less compression of color gamut.  While not the same (compression) methodology, Nikon RAW vs. compressed RAW also offers a tradeoff between file size and image detail. 

Yet, in print is the difference in "highlight detail" supposedly compressed
by Nikon visible to us?

Probably not ... EXCEPT if your post processing needs/uses that 'lost' detail. 

For example, after shooting, you find some interesting detail in an area of the image ... you crop to select that part,  adjust the levels and contrast ... and find that you don't have the shadow detail you expected.  As an example, a shot of a bird in it's nest might be in itself a great shot ... but then back at home, you see that you also have a chick emerging from the shell ... and want to make that portion of the image into a print ...

As I said before, if the scene has no motion (landscape, architecture, macro, sunset, clouds, ... ), you should shoot uncompressed. 

OTOH if the scene has action, movement, ... anything that needs a faster frame rate to get the perfect shot, decisive moment, the right expression, the foot sinking into the kicked ball, ... then you would want to shoot compressed. 

That having been said, too bad that you won't always know in advance ...

--Martin