tiff output dpi issue, file reverts to original dpi when exported as a tiff

I use aperture to occasionally process jpeg files for use in corporate newsletters. Most files arrive as really poor jpegs with a wide range of native dpi set in their exif/metadata. After image correction in aperture I then export as cmyk tiffs set at 300 dpi.
Unfortunately;
output dpi does not hold on imported jpeg files (have not tested on other types) when exported with metadata included, in this case it reverts to original image dpi as set by originating software.
same files when exported without metadata box ticked retain dpi as set in export preset.
this does not occur with files imported from my camera but files coming from third parties.
not apparently affected by camera type.
I have also just repeated this with my own files exported with and without metadata at 300 dpi, then all reimported into aperture, and then re-exported as tiffs with a different dpi (say 150). Those exported without metadata box checked export at new dpi setting. Those exported with metadata box checked retain dpi of 300.

I have sent feedback to Apple but would like to see if anyone else could confirm this behavior or not (in case I have a local problem).

10.6.3, Aperture 3.02