I have taken corners as hard as I can with my Z and I don't worry about the tire popping off. The tire flexes alot though. If you were to race 1 or 2 races a year I wouldn't get beadlocks, save your money for shocks or an axle or something. I've never run on a MX track so I don't really know how if the tires would pop off on the track or not but I have been to one quad race and I don't recall all the riders having beadlocks and not one tire came off the entire race.
Although beadlocks look really cool.