In regard to China vs Korea, you can look at my thread in the Rescue Squad section. It's titled "GN rebooted after freezes..."
GN rebooted after freezes, even worse after hard reset, now hrs later seems ok
My old phone which is mysteriously working fine now is a Korea model purchased in December '11. It's build is IMM76K. Excellent reception ever since 4.0.4 was loaded. The refurbished replacement that had literally off/on reception was from China and build number IMM76Q.
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