IPhoto to Aperture Library Transfer Oddity

Question

Or maybe I should have just said iPhoto Library oddity, since Aperture seems fine, and in the end, seems to have done what it should have.
Let me explain:
A few weekends ago, I started to transfer my entire iPhoto library from iPhoto v7.x (current version) to my Aperture v2 library. I started my iPhoto library over three years ago, using iPhoto v5 and OS X 10.4, later upgrading to iPhoto v6 via iLife ’06 in mid 2006, and finally iPhoto v7 via iLife ’08 last Fall. I then upgraded to Leopard and Aperture v2 this past Spring.
After transferring some 46,000 photos (with most being RAW + Jpeg pairs) from iPhoto to Aperture, I noticed that a there were a large number (approximately 1,800) of stacked photos were one photo was an iPhoto Original RAW photo, and the other was an iPhoto Edited RAW photo. The curious thing is, I didn't edit all of those RAW files in iPhoto, I only edited a select few dozen of them. It should be noted that all of the edited and original Jpegs pairs were also stacked, and the orientation of all of them looked fine.
As it turned out, all of these mysteriously edited photos were shot as verticals, none were horizontals. And when looking at the unstacked pair, the edited photo was properly rotated, but the Original iPhoto RAW photo was not, despite having its orientation listed as portrait. When I rotated an Original iPhoto RAW photo to correct it, the orientation was changed to landscape, even though the photo was displayed in portrait mode.
Upon further digging, it seems that all of the vertical photos that were imported into iPhoto v5 were affected, as were some of the vertical photos that were imported by iPhoto 6, but none of the photos imported be iPhoto v7. I don't remember the exact dates that I imported them and when I upgraded iPhoto, but the timeline seems close.
I also noticed recently when using iPhoto that the info display panel listed some of the RAW photos as “Jpeg (From Nikon RAW)”. I have not spot checked these files yet, but I suspect that these are the photos that resulted the creation of the Original & Edited iPhoto stacked pair in Aperture.
I do realize that iPhoto converts RAW files to Jpegs if you edit them, and I would expect that it does not when you don’t edit them. However, it would appear that iPhoto v5 always did when it rotated them, iPhoto v6 did some times, and iPhoto v7 doesn't.
I’m puzzled as to how these RAW files got edited in the first place.
I can only guess that it happened as either:
1) The result rebuilding the cache at some point, or
2) Possible as a result of a conversion process for the iPhoto updates, or
3) How iPhoto handled RAW files, particularity with iPhoto v5.
But as to why these particular files were affected, and most of the vertical shots were OK, I don't know. Any Ideas?
As for the iPhoto edited RAW photos, I plan to delete them since there doesn't seem to be a point in keeping them, because I have the original RAW file, and the original and edited Jpeg versions. They were easy to find using keyword and Aperture excellent filtering tool.
Incidently, I've also had some problems with the "Black Frames" problem and also the "Unsupported File Format" error with photos that were directly imported into Aperture. I hope that my photos are not corrupted.
Other than that, I'm really liking Aperture2 a lot!

Answer 1

My iPhoto library shrunk drastically when I switched to Aperture, from around 13.8GB it dropped to 9GB. I was worried at first but everything appears to have showed up.
The only things that I can attribute it to is the fact that when an image is imported into iPhoto with auto rotate data, the image is duplicated before it is rotated in Aperture it is not.
iPhoto duplicates the image on virtually every modification.
My iPod photo cache was quite large as well, but Aperture does not import this.
Videos you may have in iPhoto will not be imported into Aperture.
I also get the feeling that preview and tumbnail data is more optimized in Aperture.
If you are unsure backup your iPhoto library to an external drive as a read-only disk image, then if you find any problems with your photos in Aperture you can go to the disk image and get them.