I don't know if there are many Topaz users on here, but I had a tech support session with them and thought I'd pass on a bit from what I learned. I was having issue with both Fusion and PhototFXlab stripping the metadata from my photos when I exported them out of Aperture. I was able to get PhotoFXlab fixed (new version, let me know if anyone needs it, it's not been released yet), but I was told that Fusion, when set as a plug-in editor, will always strip the metadata. The tech did not seem to think Fusion would be updated to fix this problem. So now it looks like you either need to send the photo to Photoshop then to your Topaz Labs plug-in, or use the $80 PhotoFXlab, which is a great standalone product on its own.
You also can copy-n-paste (lift-stamp) the metadata from your original to the version returned by Topaz to your Library.
Photographer | https://www.walterrowe.com | https://instagram.com/walter.rowe.photo