There's two main reasons to prefer 2.4 GHz to 900 MHz. First, there's more spectrum available (100 MHz vs 26 MHz). More importantly, though, the 2.4 GHz license

There's two main reasons to prefer 2.4 GHz to 900 MHz. First, there's more spectrum available (100 MHz vs 26 MHz). More importantly, though, the 2.4 GHz license-free ISM band allocation is worldwide, whereas the 900 MHz allocation is Region 2 (the Americas) only.