I tried Aperture 3.0.2 yesterday and the updates seem to have solved all my problems. The memory leak problem was indirectly solved by Apple's "ProKit Update 5.1" available from Apple directly.

In the interim, I went back to my( 9K+ images) Aperture 2 image library and rebuilt it. I also deleted all of the "AP.thumbnails" files and let Aperture 2 regenerate them which reduced the size of the library package significantly.

After all that "due diligence" I discovered that the A3.0.2 trial version does not permit updating older version libraries. So I experimented with it by manually importing approx. 2,500 images, mixed RAW and JPEG. I was happy with it at that point so I bought the license and successfully converted my big A2 library.

With the manual import I discovered that A3.0.2 now recognizes Adobe ratings for files that have not been managed by previous Aperture versions.