Managing my photo librarys

Lightroom can have libraries while using photos stored in a folder system you specified.
I have a library for every year and have subfolders in Finder (or on the external HDDs) for every year, month and day and location.
Example:

External HDD

> 2010​

> 2010_05​

> 2010_05_12_London​

 

iPhoto and Aperture aren't really meant to be used in conjunction with one another. The basic idea is that you move from iPhoto to Aperture. That being said, iPhoto will only ever use libraries and that is that.

Aperture on the other hand can do what it calls a "referenced library", in other words, you manage the physical location of the photos and it handles the edits and other stuff it handles. In this way it functions much like Lightroom.
The best part is you don't have to start completely over (unless you want to). You can simply import new photos per usual, but in the drop down choosing where to store the files simply select your own location.

I hope that helps.