I'm not a fan of ripping people off; the guy who sold me the phones says that's what they tell everyone to do if they ever want to upgrade. He said that it's how their warranty works (and admitted it's kind of stupid) and that they don't care if a customer purposely damages them for that reason.
Uh-huh, I'm going to say the person that told you this was doing his best to get a sale period. I bet you have a number to call to claim the warranty yes? Call them and see if they think that's "okay" and acceptable under their policies. I'm sure you'll get a very different answer.