Are you going to be using class 2 for your SD cards?
Class 2 is super slow. You should be getting Class 10.
To all of those that want to use SD cards for storage you have to realize it's not that reliable. Failure rates are way higher than an external. There are plenty of small external drives that will give you 10x+ storage and much higher read/write speeds for the same or slighty higher price. It's a much better deal.