Having used Aperture and Lightroom, I have to day going back to a raw converter that doesn't also rate and catalogue images, plus having to store multiple 'conversions' rather than just the metatdata is a real bore. I tried Silkypix, Bibble, Olympus Master etc last month to check I wasn't missing anything in quality.
The answer was no I wasn't AND I was gaining 'hours' in usability. I've stuck with Aperture, but Lightroom is nice for Windows users.
PS O Master is the slowest and clunkiest of the lot.......