Hey thank you all for taking the time for your advise.
Here's something I found from a photography book in regards to the memory question. BTW I went with the 8gb.
The author doesn't understand risk assessment. The fact that you're using two cards changes your risk profile. To understand your risk profile, you have to understand the failure modes of each single point of failure and balance the cost of addressing those risks with the likelihood of a failure at that point in the chain. I'll take the risk of not getting a shot because I didn't exercise good shot discipline over the risk of a bad card every single time.
Here's one place where I disagree with his assessment:
"It's just as likely that a 4GB card becomes corrupt after, say, 2GB of photos as it is for an 8GB card to flake out after 2GB of images..."
Now, I haven't pulled apart a card to see, and it would most likely depend on the model of card- but if the memory area is roughly the same size, then the higher-density card will have more memory in the same area- that means that a physical flaw in a particular area is more likely to affect more of the card. Plus if the failure mode is in 1 out of every N cells, then with twice the number of cells, I think your chances of failure go up- but the assessment of course depends on what fails in the card- and I don't think the author is thinking beyond a memory locationv failure.
While memory card failures are rare, they do happen- let's say it's a catastrophic failure in the controller logic on the card- now if *all* your images are on that one card, they're all gone. If half your images are on one card and half are on another, you've still got half your eggs, it's not a myth- but there's a cost- you have to carry more cards and you have to switch them- though generally the cards are cheaper. If you're worried about missing shots because of switching, then you can exercise shot discipline or you can take the risk that the card goes and you lose it all. The chance of two card failures is significantly less than the chance of one card failing (even less so if they're purchased at different times.)
At a time when dense cards are new, they may be made on a smaller process than older less-dense cards. Again, the chance of failure tends to go up, as do the effects of failure.
As far as two cars to one location- there's a specific reason that the President and Vice President of the United States are not legally allowed to fly together.
Also, we're not just talking about card failure due to defects- you have one card and you lose it, no more shooting. You leave the first in your pocket and the second in the camera and the pocket goes into the wash, you've still got the second (I tend to download only my full cards, and get the images off the camera at my next download window unless the images are part of a single shoot where I have to deliver the results, in which case they all come out the pocket immediately. Your computer has an issue and the card gets corrupted logically- one card, 100% corruption...
The author is perfectly ok to take the risk themselves, but labeling it a myth and advising others to follow their path is a least naive, if not reckless.
