The class of travel on your ticket has nothing to do with the order of being offloaded. It in fact is just used at the booking stage & it allows the company to limit the number of staff tickets available on a certain sector. The order of offloading,should it be required, is still dictated by the 'B' number & provided you manage to book yourself on the flight then on a leave ticket then then order of offloading is still as per the GOM. Don't let the wonderful GF ground staff tell you anything different.