I have purchased a rhino 650 but had trouble using it on the UHF repeater channels. On testing it against another UHF CB I found that it was broadcasting on the receive channel and receiving on the broadcast channel (for instance for a channel 6 repeater is is transitting on 6 instead of 36 and receiving on 36 instead of 6). This means that the radio cannot communicate via repeaters or use the repeater channels to talk to other CB radios (let alone other Rhinos).
Garmin Australia are aware of the problem and say a patch will be released via their dashboard utility but I am still waiting.
As it stands, anyone wanting to use the radio functionality had better not be wanting to do it via a repeater. It severely limits the usefulness of the units in any more remote or hilly area where you want to use a repeater to extend range.
Here's waiting for Garmin to do a fix!