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8 GB is the sweet spot IMHO. If you really need 16 GB then most likely you don't need a laptop but a desktop/workstation.
 
RAM is everything

I've just understood that the RAM is the main point. Whithout the RAM capacities fitting to your needs, the computer will be a torture. I've been using a PC notebook for 8 years and have just swift to MBA. But a MBA with 4 Go. And I wonder if 4 Go will be enough to run the next OS coming after Maverick. As someone got any prediction about it ? Should Apple keep OS RAM appetite growing ??
 
All about the Ram

You won't really notice the difference in processor IMO.

I went with 16GB Ram and luckily I did. My usage is very similar to yours (Aperture, PS, AI, FW, RCT III, Lots of Tabs open) - not all at the same time obviously but using 1-4 of those at a time; and would be paging out a lot if I didn't have the extra.
 
I'm not choosing between 8 or 16 GB RAM, because I will go with 16. But I don't know for how many years will be 16 GB RAM enough for photoshop, lightroom and some other apps opened at the same time (like web browser). Because the needs of programs are increasing.
 
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