I've returned. Back to Aperture from my brief sojourn with Lightroom. There are benefits with each, and concerns. Yet the biggest con with Aperture may in fact be a pro in disguise. I was disappointed with the delay between market availability of new camera bodies and Aperture support for processing the RAW files. In my case it was support for the Panasonic G1. It is now supported. The lag will cause me to hold off on purchases of new camera bodies, which I guess is a good thing. I'll be more prudent.
I'm no longer faced with the scenario of converting some 30,000 pictures into Lightroom or the alternative, supporting both Aperture and LR. It is realistic to consolidate everything into Aperture. I have much fewer pictures in LR and therefore a less daunting route. A big relief; now I can get my database in order.
One of the factors that played into the decision to return was the addition of the Faces and Places features. Many pictures include people; all have a location. These features will reduce the time to tag pictures and thus improve the workflow; a welcome prospect.
At this time, Aperture 3 is humming along deep into the process of scanning my photographs, looking for faces, which I will subsequently name and it will tag. This is a learning step; at some point Aperture will be able to name the faces automatically. Aperture reports it has identified 47,809 faces.