the small swivel ones I have (pale blue colour, are goodness knows how old, both came from boot fair purchases and showe a fair amount of wear, but both the brakes on the swivels still operate on the lock arm, so even though they are no name brand, and have had years of mistreatment they still work ok, so on that basis I wouldnt worry overly about the swivel bases, the more modern alloy ones with rubber jaws, on the basis they have a clamp screw on a ball joint, I would rate those as OK for light use, and the big beasties of bench mounted vices, well I hammer against those all the time and never managed to break one yet.