Are there any risks in doing an unlock of my iPhone 3GS? I'm on baseband 05.16.05 and on IOS version 5.0.1 and I know that I need to re-flash to baseband 06.15.00 to get off of the AT&T network and be able to use any sim card. I've read in some places however that once you downgrade to the 06.15.00 baseband, then there's no coming back. Is that a bad thing? I've also read where some users complained of losing their GPS. I'm just wanting to make sure before I take the plunge.