IPhoto 11 vs aperture - Any Reason to use Both?

Question

Hello Forum - I have basically used iPhoto for my personal pictures and Aperture for my professional pictures for some years now.  When iPhoto came out with Faces, I loved it and added a lot of old scans and new photos to that library.  However, with Faces and Places and other functions now in Aperture, it seems like one library may be a better way to go.  I have about 22K photos in iPhoto and 18K photos in Aperture. 
Somehow, when I imported my pics into iPhoto, the setting for 'importing photos into the iPhoto Library' was unchecked, so I basically have 18K referenced photos in iPhoto.  I had always used 'referenced files' in my Aperture anyways, so I suppose that's just as well - especially if I want to import those photos into Aperture.  In fact, I was told by Apple tech support that they had never heard of anyone using referenced files in iPhoto who didn't have a problem with them.  So far, I must have been lucky, because I didn't have any issues until recently, and then it was due to me editing some of the original masters in Photoshop and then iPhoto couldn't re-link them even when I pointed it to the right files.  (getting iPhoto '11 fixed that - I was using '09) 
I also have another 10-15K photos to import into one or both databases once I've made a final decision.  As silly as it sounds, the one thing that iPhoto can do that Aperture can't is make calendars and cards.  But my family really likes their calendars, so I don't want to give that up.  Can I import everything into Aperture, then keep iPhoto and access the Aperture library just to create calenders and cards? 
I'm seeking the advice of users who may have been there/done that.  Are there any land mines I need to be aware of if I want to import my referenced iPhoto library into my referenced Aperture library?  Is there a proceedure I need to follow?  (other than described in the help section for importing libraries, etc.)  I never vaulted my Aperture library, and I never used the editing tools in either Aperture or iPhoto.  (I always use Photoshop for editing)  Thanks for any feedback!
R Garside

Answer 1

From what I could discern, it sounded like she meant that the two libraries were shared - as opposed to all the data from iPhoto being imported into Aperture.
She could have meant the old scheme (before Aperture 3.3): Then the recommendation was to import referenced and the two libraries shared the original masters. But that approach has been very risky and was meant as a temperary solution while deciding if to switch to Aperture or not.
Or she meant, that the shared library format: each application can open the other programs libraries - they can both use the same libraries.
Do you know if there is a 'merge' option (which I will assume means Aperture shares the iPhoto library but doesn't actually import all the files)
Aperture has a "merge " option when importing libraries, but this is very restricted. If Aperture imports a library that already has been imported earlier and than changed, Aperture will try to recognize the changes and only import/update the changed images and projects or other library items, if you select to "merge" and not to "add". But when you are importing a library that Aperture has never seen, it will not be able to recognize duplicate images and you may end up with  importing duplicates.
or if when I import an iPhoto library, all the info comes across into Aperture with no more technical need for the iPhoto library.  (aside from viewing calendars, etc. created in iPhoto)
When you import a library as library, all metadata will come across, as far as possible.
After importing a library you could delete it, but keep a backup copy!
In my case, both my iPhoto and Aperture libraries are referenced, so I would want the images I'm bringing in to be referenced as well.  Do you know if I have to handle the import differently?
Also, the images will be imported with the same file status they currently have: referenced files will stay referenced, managed files will be copied. There is no option to control the file status, when you import a library. If you want to import a library referenced, you have to make the source library referenced.
I can't find it in the help section and I'd hate to do the import and then discover that it did so by making the photos managed. There is very little info in the Aperture help regarding importing libraries - it only really talks about sharing libraries.   Thanks for any light you can shed on the subject. 
If you import a large managed library and want to import referenced, relocate the originals in the source librar. To do that for an iPhoto library you have to open t in Aperure and use the "relocate originals" command.
Regards
Léonie