WE can not tell you what you should do - and I do not clearly understand waht you want to do
as to how things work if that helps you figures out what you want, the PEN E-P3 RAW has been supported since OS X 10.6.5 - http://support.apple.com/kb/HT3825?viewlocale=en_US&locale=en_US - so if you are upto date with RAW support updates there should be no problem importing the photos to either version of iPhoto on eiother computer.
If you want to share photos between different devices easily then I think you should upgrade and use PhotoStream on all of them - I can not imagine an easier solution
REquirements and FAQ are here - http://support.apple.com/kb/HT4486?viewlocale=en_US&locale=en_US
Switching to Aperture wil not change RAW support - both iPhoto and Aperture ave identical RAW support - Aperture has many advnatages but alos is more expensive and has a longer learning curve
Hope that helps