I've been researching this and may have found a viable solution to editing images in ACR from Aperture. I've tried this in LR4 and it works. My intent is to dump LR4 and use Aperture 100% of the time.
Take a look at this article and let me know your thoughts.
The advantage that ACR has in PS CS6 is that it has the same controls as LR4.
http://michaelballphoto.com/post/24874237538/aperture-and-camera-raw-rou…
Also, I did find a program called Catapult from Brushed Pixel that acts as a plug-in to Aperture
http://brushedpixel.com/catapult
The only problem with that workflow is that you must crete a TIFF file each and every time you want to make that trip … for myself … I am constantly seeking out ways to reduce the need for derivative files and accomplish as much with the RAW files themselves as possible and forego the need to create so many redundant files …
Other than addressing noise reduction on a few marginal images or when compositing a multi image collage … I am using Ps much less with each passing day … I am also discovering that the RAW processing in Aperture 3 really isn’t all that inferior to Lightroom … in fact I am learning more and more that there is little to no difference on the majority of my images … I find, if I pay attention to details when creating the images in-camera, I have far less need for any additional horsepower after the fact … that’s not to say I wouldn’t expect or be accepting to any improvements Apple would like to offer in the future for Aperture …
What I will miss when I leave Lightroom behind is first and foremost, the Print module … I would have bought Lr1 just for that feature alone … IMHO it is one area Adobe finally got right because it is still an atrocious conglomeration in Ps … and a few minor nuances in the Library module like auto advance after setting a star rating or color label for an image when doing a first-pass edit after a shoot …
All-in-all … when I am using Aperture, I rarely if ever have the desire to jump over to ACR or Lightroom …