Unfortunately, it is not possible to utilize your ACR edits listed in the XMP file if you move to Aperture.
Basically, the issue is with the different companies design of RAW rendering which do not read each other's edits.
There is some support for DNG, but I would not recommend this path as there are a number of threads where users have had poor results. Apple's support for the format seems more like a stop-gap for users who purchase new cameras and may need to wait for the Camera RAW compatibility updates to be released for OS X before Aperture can recognize and render the RAW files.
I also moved to Aperture from a Bridge/ACR/Photoshop workflow and decided to simply backup my former work to an archive drive and then render all the images to JPEG for importing into Aperture. Since I am happy with the work I completed in the Adobe workflow, the JPEG renders fulfill my needs and Aperture allows enough tweaking of the images without degradation for future use.
All new images are of course either RAW or JPEG images imported directly into Aperture and I run a Managed library with all images inside the Aperture library package.
One other option you have (and that I thought about as well) is to keep the images in Finder folders and run a Referenced library where both Aperture and Bridge can access the files, but I personally saw no real benefit as Aperture offers the organization of Bridge and the non-destructive editing of ACR with a much nicer interface - IMHO. 😉
Sorry I don't have a better answer for you. 😟
