What is the best way to expand a MacBook Air's 128 GB capacity? A 64GB SDXC card or a 3.0 64 GB thumb drive? Which is sturdier and less likely to fail? I realize it isn't possible to internally increase memory, so I am looking for people's experience. Is it easier to walk around with a MacBook and work with a SDXC card or is a small thumb drive the way to go? Any recommendations on card or thumb drive manufacturers that have a reputation for reliability?