I ordered my new VS with four-wheel discs (in 2013), mainly to avoid the hassle of adjusting rear drums. I ended up, not surprisingly, with the full Empi treatment - Varga calipers up front and no-name mystery components on the back.
They do stop OK, but I don't know if any better than a properly adjusted front disc/rear drum setup.
I've never braked hard enough to lock up all four, as the fronts lock very easily and I usually ease up on the pedal when that happens. They do pull pretty evenly, are easy to modulate, have a firm pedal, nice feedback through the pedal, and generally perform well.
But because of general suspension and traction limitations with this car (compared to a modern 'performance' car), I drive it pretty gingerly and try to avoid aggressive braking. I think it's a car that rewards a smoother driving style - advance planning into corners, gentle inputs, gradual transitions, and looking as far ahead as possible.
The Empi rear discs weren't without problems - mine made awful noises until I found better pads, VS installed them so they hit the frame, and one of the cheesy stamped brackets caused an axle leak - but we eventually got them to work. As usual, there's better stuff out there for more dough.
PS: I've got four-bolt wheels and swing axles.