I am running GP on 4.1 and I recently reformatted my MBP. I took all precautionary measures and copied all recent backups. After installing itunes and getting everything set up how I like it I went to sync my iPhone, but as usual it tells me I have to erase and sync. So I tried restoring from a backup I have, which worked fine. When I added a couple new albums to my library I wanted to sync them, well I tried again and it still tells me I need to erase and sync. If I erase and sync won't it force me to update to 4.2.1? If I did that could I still restore from a previous backup and be able to properly sync again?