Wheter to use one large memory card or multiple smaller ones is a question most digital photographers have to ask themselfs at one point. The choice is almost as debated as Nikon vs. Cannon but I still would like to give my personal hint about the matter.
For simplicity we start of with a real life example of a photoshoot where a photographer is our for a full day of photographing a forest. When the day is over and the photos is about to be imported to the computer the memory card have become corrupted by moist and no photos can be imported. Using a large card available today perhaps one thousand photos would now be thrown away.
If the photos instead was stored on multiple smaller memorycards there is a great chance that not all cards would have broke at the same time and some photos could be saved. And this is the reason to why I use multiple cards instead of single large ones. It makes the risc of loosing your work a litle bit smaller.
Tip from the Autor » When taking photos on a trip or in places which are very crowded, do not keep all your memorycards in the same place! Buy a couple of small hardcases for your memorycards and keep some in your bag and some in a pocket for example. This will spread the risc even further if you for example loose your bag by mugging or just bad luck.