So you think going above 1000mah could be dangerous to the device?
The charger supports 2.1A, or atleast that's what it says.

(When i had an S3 too, i set usb input charge to 850mah because i had usb 3.0 on my pc and it was charging just fine!Don't know if it matters or not though.)
I know, the chargers for tablets such as iPad has output capacity of 2100 mA.
And I think, stock value set to 1000 mA is for good reason like archive minimum charge time and less dangerous to the device and battery.
One thing I sure is that, if you charge with 2.1 A, your battery will probably heat up like hell, and that high temperature is NOT GOOD for Li-ion battery as we have for i9300.
For myself, I always set it down to 800 mA for over night charging (I guess you won't set up a alarm in the middle of night to wake you up to unplug the charger, will ya? ). And I do use 2.1 A charging, in case of EMERGENCY like I have to go out for long time and my battery is low so I have to make the battery charged as much as I possibly could. But still, it is NOT recommended.
Sent from my GT-I9300 using xda premium