Reply to Is 4GB of RAM enough? - Retina MacBook Pro

The screen on my MacBook Air 11" (mid-2011) has finally decided to die. It's usable from time to time, when the screen doesn't crap out on me, and when connected via Thunderbolt to an external display, but unfortunately I can't use it for DJing anymore. I'm using it now as a home theater laptop and constantly keep it connected to my TV.

I am in the market for a new Mac laptop now and while my MBA 11" with 2GB of RAM ran Traktor perfectly, I'd like a bit more of screen space. I have my eyes on the following:

1) 1.3GHz i5/8GB RAM (mid-2013) 13" MacBook Air ($1099)
2) 2.4GHz i5/4GB RAM (late 2013) 13" Retina MacBook Pro ($1299)
3) 2.4 GHz i5/8GB RAM (late-2013) 13" Retina MacBook Pro ($1499)

As this laptop will be strictly for music/DJing (no DAWs) and nothing else, is it worth spending the money to get 8GB of RAM or will the difference in performance for DJing uses be negligible? When I play, I only have Traktor running (sometimes Mixed in Key open as well).

I plan on keeping this laptop for at least the next two to three years. I would prefer not to spend over $1300 for the laptop, so Option 2 is what I'm leaning towards, but I don't want to end up in a position where I have to upgrade in a year or two.