I have a Grom and it works but the next and back buttons on the radio don't work very well with it. Sometimes they work, sometimes they don't, and the back button usually goes to the next track instead of backwards. I suspect their firmware is buggy in regard to handling the next and back messages from the head unit to the CD player.
Probably a stupid question... but does installing this Grom make it so you cannot use either the Cassette or the CD changer? Or can I still access both of those? I am assuming it completely replaces the use of the CD but one can still use the radio/cassette if so inclined?