Just stumbled upon this article titled "Maximizing Throughput in ZigBee Wireless Networks through Analysis, Simulations and Implementations".
Abstract"”ZigBee is a robust wireless communication standard managed by the ZigBee Alliance and based on the standard IEEE 802.15.4 physical and MAC layers. Certain applications of ZigBee, may be critically limited by its designation as a low data rate standard. This paper describes a three-phased approach for measuring and attaining maximal throughput in a ZigBee wireless network. The phases consist of: 1) practical calculations, 2) NS-2 simulations and 3) hardware implementations on Ember Corporation EM2420 based development equipment. The first two phases provide an approximate practical upperbound of 120kbps. The final phase is targeted to realizing maximal throughput in an actual hardware implementation. The results reveal maximum throughput for a ZigBee wireless network reaches 110kbps for well-refined hardware designs. Finally, a set of desirable traits is presented for future ZigBee hardware designs concerned with achieving maximum network throughput.
110 kbps matches well to BitCloud's real performance.
Reading this article might help anyone wanting "advertised" 250 kbps from ZigBee network.