Just ran some tests: AP3.4 vs. PSE8 vs. Pixelmator. There are differences between Aperture and PSE, but they're subtle. And I can't find any way to make PSE use Color Sync profiles, it seems to be limited to the built-in profiles.
Aperture and Pixelmator show significant differences when Px is using the proper paper profile, but they look almost identical using AdobeRGB in Px. So yeah, it looks like Ap is using AdobeRGB even when you have something else specified in the print dialog.
I'm wondering if this might be fixed by trashing Aperture prefs and/or the Aperture cache, if anyone else feels like testing.
Uh oh, now I've done it. I changed the color profile in the Ap print dialog, hit print and save for the print preset to force Ap prefs to update, but canceled in the printer dialog because I didn't want to use another sheet of paper. That dumped me back into the Ap print dialog, but both the cancel and print buttons just beep at me, nothing happens. And you can't do anything else in Ap until you get rid the print dialog. Sigh…
Update: deleting prefs and cache hasn't helped. But the profile I had been using was still selected in the Ap print dialog, so apparently that's stored somewhere else. Doesn't look like it's in any of the printer prefs, so I don't know what to try next, other than send feedback to Apple.