Can I get predictable/consistent latency using XBee Pro 802.15.4 module?

Hi, I’m interested in working with 802.15.4 (just getting started here) in a point-to-multipoint application. I simply need to broadcast an incrementing sequence number to several nodes within a room periodically (say once per second); however I need to know that it is being sent to each node consistently (same latency) each time. I assume I would use the GTS (guaranteed timeslot) in 802.15.4 for this, and I was wondering if this module allows me to program at that level.
Note, I assume I would not use ZigBee for this if I want to achieve better latency and determinism true?
Any help/thoughts would be appreciated.
Thanks
Ed

Ed,

Correct. Zigbee is going to be less deterministic.

See the xbee product guide for 802.15.4 firmware. Pg. 31 under the ‘active scan’ command has an interesting blurb about this:
http://ftp1.digi.com/support/documentation/90000982_G.pdf

GtsPermit 
RSSI (RSSI is returned as -dBm)
TimeStamp (3 bytes) 

A carriage return is sent at the end of the AS command. The Active Scan is
capable of returning up to 5 PanDescriptors in a scan. The actual scan time on each
channel is measured as Time = [(2 ^SD PARAM) * 15.36] ms. Note the total scan time is
this time multiplied by the number of channels to be scanned (16 for the XBee and 13
for the XBee-PRO). Also refer to SD command description.

Keith