I found some information from another thread that the x00 series has better GPS chip than the x05 series where it locks onto the satellite quicker and more accurate. I have both the 705 (bought way back) and the 500 (last year), I would say the 500 is a superior cycling computer, just without the navigation features which I have never used in all the years I owned the 705.
Originally Posted by
pallen
The main reason to do the 705 or 800 is the ability to do navigation -- if you want the Garmin to tell you how to get somewhere. I have a 705 and never use that. A 500 would have been fine for me, but I found a 705 for almost the same price as the 500.