I'm on stock with goodies ROM, and I've seen glimpses of it here in northwest Fort Worth TX, but doesn't stay on long enough for me to run a speed test. My wife has the SGS III, stock not rooted and it shows the same. Just pops up 4G for a couple of seconds and jumps back to 3G. Annoying, but at least I know it will still at least attempt to connect. I did take the OTA update and rooted afterwards so I do have the new radios and firmware updates.
Update: still running stock with goodies 1.74, been on 4G on and off thru the Fort Worth TX area. Works pretty darn good. Just wish they'd turn on the towers close to me so I don't have to drive around looking for good data speeds.
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