Using iPhoto Library in Aperture 3

Currently I have two separate photo libraries, each containing the same photos/videos in both iPhoto 11 and Aperture 3 (latest updates for both).

In order to conserve HD space is there any way I could eliminate say, the Aperture library and have it use the iPhoto library as default? Each library comprises 24K+ photos/videos; however, iPhoto is the only one which can play certain of the older videos, Aperture won't play them. There is roughly 80 to 85 GB in each library due to the amount of items. I could keep the iPhoto videos in iPhoto for reference purposes and remove same from Aperture, but that means I am still running with two libraries.

What would be likely problems if I were to remove my current Aperture library and have Aperture use the iPhoto 11 library instead? I am running low on HD space and don't wish to use an external drive to store one of the libraries; however, I do use an external drive for Time Machine backups.

I am wondering what problems I would encounter and if there would be any benefit to this scenario.

Perhaps some feedback would help me to decide. Either I can eliminate the iPhoto library or the Aperture library. Thoughts and recommendations would be appreciated.

Thanks.