I'm no expert, but it's my understanding that Clarion is real good. Why do you want to replace it?
What about a newer model Clarion?
That being said, I just put in a whole new system and put in an Alpine Deck, this one
I heard that alpine was awesome and the x100 is super ipod compatible. I don't even have my boat back from installation to review it, but I'm guessing "sickness!" lol