I don't have the 3g, but I don't think there is a way to turn it off on the non-3g. I just installed R720XXU2CPC5 that became available the other day, and now my auto brightness is jacked up. It is too dim much of the time, as settings 1 through 5 are the same level. But sometimes 1 through 5 act normally. Too soon to know for sure, but it seems as if Samsung changed it such that my S2 defaults to the dimness of level 1 in dark situations, even though it is still set to 4. Not pleased with this change.
Had the same problem here (among a multitude others). I normally keep my S2 Classic on like 2 or 3, but found that it would go to darkest level for 1-5 for no reason. Had to do a light reset on the watch and then reset it up on my phone. This fixed ALL of my problems (Light issues, Weather not working, spotty notifs). Only thing is, I have like 130+ watchfaces and the setup, restoring previous settings, took literally a few hours. Keep that watch on the charger while you do it...
Sorry but, it is my Friday and my brain is fried. Explain the re-sets you did. What/how do I do a "Light Reset" on the watch. and what did you reset on your phone? Did you uninstall the gear manager or do you mean you started like you just got the watch.