I am currently going through the APM/Reach integration and I was surprised by a recommendation stated in the tutorial:
It is recommended to use Reach as a second GPS unit only.
Why is that? Is there any downside to using Reach as the only GPS? As far as I understand, Reach will provide a really accurate position whenever the base corrections are available, but otherwise it will still provide the position with the same accuracy as a normal GPS receiver right? So why using two GPS receivers?