Before choosing any design;
First define the Spec of what information MUST be sent to a display device and what may be sent or "nice to have".
- number of pixels * colours * levels of intensity
- Pixel update time not field refresh rate.
- net Pixel rate bandwidth [MPix/sec]
Before you consider the waggle dance of XBee ( a trademark) , remember " ZigBee has a defined rate of 250 kbit/s best suited for periodic or intermittent data or a single signal transmission from a sensor or input device"
Consider if you have embedded scaleable fonts, then you dont have to transmit every pixel for each character. But if you choose analog style display of video images with text, then consider an analog communication link with NTSC converted to raster LED TV display, or compressed video in a packet Tx mode using whatever Wireless technology you desire. Also consider encryption, interference, hack-proofing and watch-dog timers to prevent public displays of bad data.
If this is say for a CMS or changeable message sign, then certainly, one can compute the latency of sending a static display update given the burst error rate of Zigbee and local density conditions and retry success rates.
Yes ZigBee is addressable to many targets, so it is ripe for creating a new standard for LED addressable remote RF controlled displays vs the old RS485 standard. Research it to find what protocols have been established already.