I and a few buddys have the rhino 530hcx, I have to say it has it's pro's and con's.
I'll start with the con's- I have had to make an exchange for a new one three times do to the speaker on the radio going out over the 4 years I've had it, one of my buddy's also had the same problem.This happened again but this time I couldn't return it because it's now discontinued,but you can still find them online. However I found away around the speaker problem by going to the push-to-talk ear peice.The topo map mini sd cards you buy pre-loaded are expensive, and graphics are ok.
The pro's- you have a radio and gps in one unit, you can poll your buddy's location and see where each other are at (great for working the area) that is one of the option's that sets this gps apart from all the others,IMO.It has the national weather channel on the radio.Batt. life is ok as well. All the other options are about the same as other gps's, like way points, electronic compass, tracking your trail, alarm clock, moon phases games, etc. etc.
Over all it's great to use for hunting with buddy's that have the same unit.IMO