Quoted from DrJoe:It really depends if you like slide saves or not. I don't, and most people I play with don't. That being said, I use nothing on carpet and casters (Pin-Butts) on hard surfaces. This way you can nudge and slap save without the machine sliding. Most tournaments are set up this way including PAPA and Pinburgh.
+1 Slide saves make it too easy to save STDM I find, and I hate pushing the machine around with slap saves and hard nudges. I like it to stay planted.
I have improved my play significantly since sticking my machines to my floor with PinButts. No more slide saves, but on any machine that I can slide save on i can almost play indefinitely if the tilt isnt super tight.