I don't trust tool-less mounts at all, regardless of whether they're drive mounts or card mounts. Screws to secure everything :thumbsup:. Rubber fan screws aren't that great either since they become brittle and snap after a year or so. If I need to noise-isolate something, I use bungee cord instead (got 50 ft of the stuff for a few bucks off eBay).
Heck, the toolless PCI clamps on my Coolermaster 590 can't even support the weight of my GTX285 if the case is standing stock still, never mind if I move it around. The clamps just pop right out. I flip them up out of the way and use screws instead.
Btw, at college, all of our Dell lab computers were stuffed inside metal brackets bolted to the tables, to prevent people from stealing them. In this case, they might help to keep things secured on a cruise ship that's pitching and rolling (I assume that's how the rig fell off the desk?).