I wouldn't expect to see too big difference between the two. They are both based on Sirf IIe/LP chipset. But why not instead of the old BU303 consider the newest BU353. It's not in store as far as I know, but it could show up any day now. It should easily outperform anything based on the older Sirf IIe/LP chipset. Here is the link: http://www.globalsat.com.tw/english/...id=20&p_id=115