I like Aperture's interface and find that it suits my needs well. However, the program is so slow and so unstable that I'm seriously considering moving to Lightroom. I have nearly 30,000 images loaded, organized, and edited in Aperture. So I wouldn't even bother moving them over. I would just keep Aperture around for working with images up to a certain date, and would put all new images into LR. But before I go messing around with LR, I'd like to know how it handles massive archives of photos. If you have a project filled with a thousand or more RAW images, will LR run like a walrus? Does LR frequently hang, crash, or do something that requires you to relaunch the application? FWIW, I'm running the latest version of everything on a 2.4GHz MBP w/4GB RAM. Referenced files are all on a FW800 drive (7200rpm). The Aperture library itself is on my internal drive. I would keep this setup for Lightroom.