I got some of the heavy duty off-road type Crocs a while back. They are great! Keep them by the door in the garage and wear them often. Very comfortable, durable and "all terrain" to boot! They replaced my "Jesus sandlas" aka rope sandals as my favorite weekend wear.
As far as sandals vs crocs, I gotta say, flip flops will be my only footwear when welding. Get a hot piece of slag in a flip flop, just kick it off, less than a second. get it in your croc, and you gotta take off the back strap. Boots btw are the worst.