As far as cases are concerned, I won't use anything but Pelican boxes for my cameras and firearms. They're a little expensive, but I spent a few years working as a whitewater raft guide on the New and Gauley rivers (Class V+ whitewater) up in West Virginia, and I've seen those Pelicans stand up to some punishment that still amazes me when I think about it - not just staying intact, but waterproof as well, you know?
On the pick-and-pluck... it's fine if you're storing an item that you're not going to be using a lot. For example, I have a multi-gas monitor in my truck. I have to keep it in there, because if I need it I'll need it with me, but I only use it two or maybe three times a year. It's been in a Pelican box packed in pick-and-pluck foam for 3 or 4 years and the foam is in great shape. For things like my cameras and guns though that are taken in and out of the case on a regular basis, the stuff just comes apart after awhile.
Good tip on the ethafoam, though. I might give that a shot.