I am using Edge 705 since May 2009. The new Edge 800 is really tempting with touchscreen and other new features and was released end of last year.
Currently. the price of Edge 800 complete with heart rate and cadence still above USD500 on ebay.
The Edge 705 served me well but still if the price of Edge 800 dipped below USD500 and the exchange rate is favourable, I’ll get one. Because I’m a gadget man!