I agree with snowmansteve, the Guru feeders have a built in safety feature to eject the feeder in the event of a snap up.
I myself fish the method a fair bit, but won't use the elastic, I cut them out. Instead I feed my mainline through the middle and connect to a swivel (running style) that way if my mainline breaks the feeder will fall off and the fish will have no more than a short hooklength to deal with.