[Tinyos-help] wireless communication speed

[João Paulo Amaro da Costa Luz Carneiro]

Hi,
I have a question related to the maximum transmission speed for the  
IRIS 2.4GHz mote.
The datasheet Crossbow provides states that it can transmit at  
250Kbps. Has anyone tested this speed?
250Kbps = 31,25KB/s
If a normal packet has a default payload size of 28Bytes and the full  
packet with headers  (if I remember correctly) is around 44B, then a  
mote needs to be able to send  (31250 / 44 = ) 710 packets per second.
The results I've experienced in my tests are very very far from this.  
The tests I made a few months ago I could send a packet every 250ms  
without packet loss but increasing the size or decreasing this 250ms  
would result in packet loss.
Can someone share results or explain me anything I could be missing.
Regards,

Joao