I have seen those, but never actually owned one. The cast aluminum Stanley versions are alot more common from what I can tell. I've never had one until recently, as when I used razor knives I was strictly a retractable blade guy, due to almost losing a thumb as a teenager with a razor like this.
I wonder why the steel ones have the holes? To let the user know if he has any blades left inside? Perhaps heavy users that go through alot of blades?