Several questions about migrating from iPhoto to Aperture

Question

I'm currently a heavy iPhoto user and am looking into migrating to Aperture. Can anyone give me a sense of what I to expect if/when I make this switch?
Here are several particular things I'm wondering about:
1. iPhoto works great as a computerized photo album for casual browsing. (I can see a page of different events with mouse-over previews, plus I can hide poorer shots so that I can just view the highlights.) Will Aperture be a step back in this department? If so, is it possible to "share" my Aperture photos with iPhoto without keeping two parallel copies of everything?
2. When I import an edited photo from iPhoto to Aperture, will the iPhoto "original" become the Aperture "original" and the iPhoto "modified" become the Aperture "modified? Is the same true if I export an edited photo from Aperture to iPhoto?
3. Does Aperture have an analog for "hidden" photos? I currently mark my best shot from a series by hiding the rest. Will I lose this marking if I migrate to Aperture or is there a way to preserve it?
4. I currently have a number of short video clips (taken with my point-and-shoot's video feature) mixed in with the iPhoto albums. (iPhoto really does let me keep everything organized in one place!) If I understand correctly, Aperture won't let me store these in my Aperture library alongside the still-photos of the same subjects. Is this correct? If so, how have other people handled this?
5. Do EXIF tags get re-read upon import from iPhoto to Aperture? I've got a number of iPhoto files which I've retroactively geotagged with HoudahGeo. Will the tagging be lost (since iPhoto is not currently aware of the geotagging as the EXIF tags have not been re-read)... or will Aperture now recognize this metadata?
6. If worst-comes-to-worst and I give up on Aperture after a few months, how painful will it be to un-migrate back to iPhoto? More importantly, what album metada (e.g. events, albums, ratings, tags, notes, dates, hidden-ness, links between original and modified versions of a photo, iWeb references, etc.) will be lost? In other words, if I were to import everything from iPhoto to Aperture, wipe my iPhoto library clean, and then export everything back from Aperture to iPhoto, what information will have been destroyed?
Thanks in advance for any answers to this long list of questions!

Answer 1

Here are several observations (read: warnings) in case anyone else is considering migrating a significant iPhoto library to Aperture...
A) Pictures marked as "hidden" appear to be silently skipped over (along with video clips, as was expected) when importing an iPhoto library to Aperture. They do not appear in the relevant Aperture project regardless of the filtering options.
B) Both iPhoto originals and modifieds are imported. The former are given the keyword "iPhoto original" and the latter are given the keyword "iPhoto modified." Each pair of photos is put into a single Aperture "stack." Both photos are given the same tags/ratings (so, for example, the un-rotated, uncropped, poorly balanced original will show up alongside the nice clean "modified" if you were to filter for 5-star images), and both files are given identical "version names" (equal to the "name field" in iPhoto). In most cases the original -- not the modified version -- was set as the stack's "pick" and displayed when the stack was collapsed. *Significantly, I could find no way of creating a view in Aperture that showed one copy of each picture, with the "iphoto modified" version displayed for photos that had been modified in iPhoto and the original version displayed for photos that had never been modified in iPhoto!* (This is, of course, the way they are shown in iPhoto.)
C) My understanding of "stacks" is that they are designed to help organize multiple "tries" at the same shot (e.g., I want to make sure that nobody's eyes are closed in the group photo, so I press the shutter six times in quick succession -- I'm going to pick a "best" one will be mostly interested in that shot from then on). This is a fantastic idea! However things get confusing if you are already using stacks to track original and modified versions (as described above)... particularly if your stack should contain six pictures plus original versions of each. Plus, as I mentioned, the "original" version is usually the default "pick" in each stack.
D) After import, "iPhoto original" versions of portrait photos appear un-rotated. Normally, my cameras (including a Nikon D80, an iPhone, and others) mark photos' orientations and they are automatically displayed in the correct orientation. Aperture appears to consider this auto-rotation an iPhoto edit and helpfully displays the "iPhoto original" always in landscape.
E) Aperture may incorrectly import events whose names contain a "/" or a ".", so if your event names contain dates, rewrite them with "-"s before importing to Aperture.
F) Aperture does have a rough mouse-over-the-icon-to-flip-through view, similar to the "events" pane in iPhoto... although you will lose your choice of which photo serves as the default icon for each event when you import your library from iPhoto, and you cannot "hide" photos from appearing in the flip-through as you can with iPhoto.
G) Perhaps it's my inexperience with the program, but I could find no way to sort the project list by date (vs. alphabetically), nor could I find any way to make a correction to a single photo's date/time.
As a bottom line, remember that Aperture is definitely not "iPhoto Plus." It lacks a number of iPhoto's features, but in exchange gives you a number of really slick tools aimed at streamlining a digital photography workflow.
I'd also encourage people to think very carefully before moving a large, well-organized iPhoto library to Aperture. You may lose a fair amount of information, and the result will take a lot of work to "make pretty" again. It does look like a nice program, though. Are you ready to relegate all of your existing pictures to an iPhoto "pre-history" and start over with a blank -- but much fancier -- slate in Aperture?