For those of you who are planning to buy a MacBook with a SSD that will likely be too small for your total data storage needs, what will you be using externally to provide the rest of your storage space? I ask because I would prefer to get only a 256GB SDD in order to save money, but I anticipate that within about 1.5-2 years I will need more like half a terabyte of data space in total. Does something like this http://www.pcmag.com/article2/0,2817,2412666,00.asp approximate what many of you will be getting? If I were to buy this and plug it into my laptop via Thunderbolt, is it going to be basically as fast as the internal SSD? Does the decision to use external storage also depend greatly on the nature of what's being stored?