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I'm using MBP 13" base model of 2009. Somehow, I feel regret purchasing it, but not regret for using it. The really appealing of 15" is the side speakers near to the keyboard. 13" is convenient in most of ways especially when you are carrying it out side.

I have an 23" FULL HD external display, but the usage is not so convenient (you have to plug the monitor to the display and the external keyboard & mouse).

It is just my personal opinion and preference to use the MBP15". My tasks can run it with the 15" screen size without connecting to an external display.

And again, I really like the side speakers of 15".
 
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