I think the GT-30 works great. It did require an adapter plug kit from Concertone but it was plug and play. I see where other people are not fond of the Concertone (Genesys) brand but I have had no problems.
My 8 year old unit, the GX500, still works but the physical buttons are 'sticky' and the unit doesn't always respond. Using the remote the unit responds every time.
I just put the new GT-30 through a rigorous test by driving over the Denali Highway (I'm in Alaska). 125 mile of rough road and pot holes and the unit still works so I'm satisfied. We had a great camping trip