Good rubber rafts such as achilles and avons are amazingly seaworthy. They have more than one air chamber, so they're virtually un-sinkable unless you manage to punch holes in all three chambers at once. They're not the most comfortable of secure feeling crafts because you're so low to the water, but I'd feel much more safe in a 12' rubber raft than I would in a 14 or 15' aluminum boat if it really came down to survival. Folding rubber rafts have saved lots of people who carry them as a last resort if their main craft sinks or capsizes. .02
david