I think only has beens who think they can latch on for a ring will go to MIA. Damp is a perfect example. Another big won't fix them though. A coach won't fix them either. They have 3 studs that all need the ball to play who have similiar skill sets. They don't play great defense either and no I don't buy the all NBA defensive team of LeBron as it was a David Stern Hype up the star of the moment award. You want to tell me he was a better defender than Tony Allen?
I think adding Perk to the Heat would go a long way toward solidifying them as the team to beat in the NBA. He's exactly the type of guy Bosh needs playing beside him, and having Perk man the middle would only make Lebron's and Wade's defense better.
I think you're wrong about Lebron's defense: he's an elite defender, and yes, better than Tony Allen. Also, Miami's team defense is very good: 5th in the NBA as of today, behind the Bulls, Celtics, Hornets, and Magic. They're #2 in eFG% allowed, FG% allowed, and 3PT% allowed. Their "weakness" as a defense is that they don't create a lot of turnovers, but if they had a shot-blocking presence inside, they'd be able to gamble more.
I hope you're right that Perk has no interest in the Heat, because I think he'd make them a much better team.