the hoses on the car are probably ok when new but for a remaped car with a few miles id defiantly go for one, they standard ones can collapse under high boost and try and suck into the turbo, closing up the air flow gap and loosing power... better turbo spool up sound, free flowing and wont collapse at high boost.+ the standard ones are like made out of chocolate cake.
Just get your VAG tuner to feel each time you're in for a service or whatever...
And the general concensus is that the other hoses are pretty much ok and only need replacing if they split at some point in the future.
I found a difference when i changed my upper intercooler hoses as well, boost felt like it came in much stronger.