Macbook Pro 15" Retina Worth It?

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Is the new SSD that much faster?

No, not necessarily.

http://www.macworld.com/article/205...-boost-to-new-13-inch-retina-macbook-pro.html

A lot of the speed would depend on the controller and the capacity. Generally 128 GB models are slower than 256 GB models, and 512 GB models might be even faster.

The late 2013 models in that graph (which are the 13" MBP, not 15") have 128 GB (2.4) and 256 GB (2.6). The early 2013 model also had 256 GB.