Horrible from what I've heard.
These radios (and many others) are Line-of-Sight (LOS). If you are in semi-steep country the radio will not work very well.
However, the Garmin Rhino Series GPS/Radio's can help you locate a hunting partner "in need".
The GPS system and the radio system on these units are two completely different dynamics.
GPS technology is relatively simple and easy to understand it's limitations.
Radio technology has been around for an eternity but most people do not understand the limitations...unless you own 40K acres and can afford to install a Repeater on the highest point.
Anyways, GPS does not equal Radio or vice versa; two completely different systems.
If you want the Rhinos for GPS capabilities, I'd buy them at that price.
If you want them for GPS and Radio capabilities in "rough" country I'd pass.
He's selling them for a reason and I would suggest you don't fall for the "I'm upgrading" line.