dubfan - You are not in the clear and never will be until you pay up. Friend of mine who 'jumped ship' got nailed some ten years down the line, pay up or domestic flights only etc.
A bond is a contract and if you sign it you have entered into a contract, contracts are legal. A bond doesn't restrict your movement anyway, pay up and you are free to go, otherwise honour the contract you agreed to, (and thereby restricted your own movement). I'm not a lawyer or even close but that is the opinion of a friend who is.