I cannot even imagine using a card less than 32GB.
I have several I rotate during my trips, that way if one goes bad I don't lose ALL of my trip pictures.
When you stop to think of the cost of cards vs. the cost of the trip and the cost of the camera, you
should be able to buy a few cards. Depending on the size of the pics in MPXLS, maybe you can
do fine with a 16GB set of cards to rotate.

I'd also be careful not to assume that just by copying them to a HD that you won't lose them, I have
had HD's go bad, one took a power hitand my whole system fried due to overvoltage.
I copy my 'important' stuff to an internal HD, AND an external HD that I ONLY hook up when backing things
up to it and then I disconnect it, and I also copy some stuff to DVD's (and DVD's don't last forever, either)
Again, when you add up the cost of a vacation/trip, it's a lot less expensive to back up the important
images to several different places - if you are into that (photography).