I hear allot about the turbo hoses, for the Freelander TD4, that they need to be changed, go faulty, ect.

Could someone please tell me when they go bad and need to be changed?
Is there any disadvantage to not changing them?

usually, they split, esp. where long one passes across the top of the engine and rubs on the screw for the inlet manifold. look for oily deposits on the outside of the hoses (short little elbow one) which shows they are leaking.

if it splits, loads of black smoke and a whistling sound as you accelerate.