Ok this has got me going to the extent that I have done some real world comparisons of my own.
I use aperture 3 not only as a raw processor but to library my final print files from PS3 or whatever. I use it for all my image file organization. This is its major advantage over LR for me.
So this issue is a dog for me as I do not generally keep processed files stored elsewhere that have not been through this route, as I use a plugin in PS3 for my printing and do not print direct from Aperture.
I exported 2 files from Aperture, original size, 16 bit, 300dpi, black point plus data etc. One as a Tiff and one as a PSD then back into Aperture for archiving.
The original 5D11 raw files show as 5023K with a 6 tint with camera default set and both import back as 5000K 0 tint.
When compared in Aperture, this small change seems to make no colour difference to my eye, but is a little more vivid or bright, AND the raw version shifts slightly in the main view of the levels inspector.
When re exporting the Tiff and PSD and comparing to the first exports in PS3, I can see no difference! And playing with the info picker shows both versions to be the same.
My conclusion is that as the final print version from PS3 is archived in my Aperture library as I saw it for printing and when re used will be the same, all appears OK.
The fact that there appears to be a change in colour temperature when exporting is more annoying than anything, especially as this can't be confirmed in PS. I stand to be corrected on this.
I make further adjustments in PS for printing anyway.
I switched the camera default off and exported a 4848K 1 tint file and imported it back and it re imports as 5000K o tint.
The answer lies in there somewhere but far more talented than me need to explain.
So is it Aperture?