3D xbee triangulation

I am an architectural grad student working on a fabrication thesis using the arducopter from 3D robotics. I am attempting to use the Xbee transmitters and receivers as a local GPS, by calculating the location within a volume with relative precision. I am thinking of using 3 transmitters mounted around the work area and one receiver mounted to the arducopter. i have been getting mixed reviews reading through other threads if this is the best way to go about this.

my goal is to have the copter able to navigate its location (x,y&z directions) in an area and be able to return to that area at a later time. Is this the best system for this goal?

I would be concerned about the comms latency of any of the Bee's or any other radio with a networking stack on it as the time it takes to send out a beacon pulse and to receive the same pulse is not deterministic.

Don't use radio for this. The only working setups for 3D inside navigation I've seen, are with ultrasonic senders and receivers (not the ultra cheap models on ebay but you don't have to order high end components).
You may have an easier time if you put the transmitter on the arducopter and do the timing calculations (triangulation) on a a laptop and then use the XBee to send the location to the copter.