We use aperture for all our photo processing (thousands of shots a month). I also MUCH prefer it to Lightroom, and nothing in the new LR4 Beta looks like it is going to change that. We find the ability to do non-destructive retouch with skin smoothing, clone and repair tools as well as RAW development turns Aperture into a one-stop shop.
If I had one feature request personally it would be to talk to Hasselblad and get the colour science from Phocus into Aperture. But that's a minor point. These days I look at images in both Phocus and Aperture, see which one gives me the result closest to the look I want, then choose that one as the basis for the rest of the processing. (Even the Phocus shots go through Aperture for retouching and export). It is almost like having the choice of two film stocks, in post
I'm actually at a bit of a loss what features I'd request from Aperture 4. More speed, obviously, always. Keeping up to date with latest camera RAW formats. Maybe negative clarity, although that's basically what skin smoothing does in a nicely targeted way.
I'm REALLY happy with Aperture, my absolute workhorse app so I just hope they keep it ticking along, I don't need any particularly grand new features.