Gremlin Solutions delivered the joystick and buttons at an incredible speed. Here's the mini button next to a standard arcade button. At first glance the mini button is perfect, I can easily fix a 6 button configuration in a small area. The microswitch is built into the button. On closer inspection I've found it to have quite a high action, and it's a little stiff to press. The action and stiffness could make rapid button bashing a little difficult, I'll have to knock up a test control panel to see how it feels.
The joystick of course looks monsterous in comparison, so I'm still on the lookout for a solid but small joystick.