So last week, my 2.5 yr old 3GS stopped holding a battery charge, and died suddenly, several times. So, being on T-Mobile, I sourced a used iPhone 4 that was factory unlocked. While I was waiting for it to be shipped, a good friend of mine who works at an AT&T store, gave me his 6mos old 4, that was locked. (he owed me a favor). While waiting for the Factory unlocked one, SAM came out and I successfully unlocked his. I used it for 2-3 days and LOVED it. Not thrilled about the tethered JB, but not a big deal. I figured I'd sell it once the factory unlocked one arrived, since its less of a headache being an actual factory unlock, and not hacked...no fear of OS updates, etc... It arrives. I do a fresh restore. Then decide I'll restore from the other 4 backup, since all of my apps, settings, are gonna get imported over, including the MMS setting I had to use iBot for, etc, that I just spent 3 days on, to work on T-Mobile. The phones are now setup identically. I don't like the Factory unlocked one. The screen has a yellowish hue, the volume of alerts and ringtones are muffled a bit and quieter, the vibrate is lower pitched and not as aggressive. And the proximity sensor is weird...I've accidentally turned on speaker, or muted calls 3 times in 2 days. Maybe the other one is the same, but the NEVER happened on my 3GS. What to do.. Prob easier to keep the JB one, and sell the FU. Not looking for any real advice, here, since only I can decide. Just telling you my experience. Great forum, here.