I'm going to sell my iphone 4 on ebay. It seems that most people recommend doing a factory restore and then rejailbreaking to preserve the baseband (015900). When I click on the restore button in Itunes, it says all info will be wiped and the newest version of iOs will be installed. Is this the correct thing to do? And then downgrade to 4.3.3 (the current iOs on the phone) ?