To allay people's fears regarding machine damage, after the stories above.
It is extremely rare for a machine to be damaged at a show by abuse from a player, extremely rare. These machines are designed to be put on site (often bars) and played without the supervision that is around at shows.
Don't let this put you off bringing your machines to shows.
I've taken machines to shows for the last 8/9 years and have never had an issue caused by a player. You're much more likely to damage them yourself while moving them.
In fact the only damage I have incurred was when I didn't have any ratchet straps to secure my 2 machines to the truck, while going to collect others, and used bungee cords - the hook broke causing both machines to fall upside down. The Metallica glass smashed meaning a huge clean-up (thanks Tel) whereas WPT was undamaged and played perfectly for the whole weekend.