None as far as i remember. You phone got problem with camera? I think you must have a certain battery percentage to take photo. If you on low battery then your camera wont work :-)

Your friend phone is rooted or not? If not, make sure the battery is above 30% before taking any photos.
If still got problem then better check at service centre

9100G will do if you don't flash custom roms. It might be even better because some user say have better battery life...

Gaming is almost non issue here as both version can play games without problem. The main choice will fall under roms category. Do you like flashing custom roms or you can live happily with stock roms.?
If you're kaki flashing type then the most logical choice is go for a non-G version.
If you dont mind stuck with stock roms then get a G version as the price is cheaper.
~~just my two cents~~

I9100G 

I believe Samsung will only release firmware update that can optimized Mali 400MP in January not the actual full fledge ICS upgrade :-)
Otherwise Samsung cannot launch SGS3 lor as everybody got ICS on their SGSII..:-P

Stock rom, it becomes smooth again after reboot, sweat, why like that one??

Already try since first day i buy. no laggy and delay at 1080p video
try with a 1080p video size 153mb mv

I sold mine at RM1400 already. You could try for a lower price of course :-)

different. root is jailbreak like tht. flash in layman i think is install. ok i guess that was a lame explaination lol i also need help in this thing. gah.

Wating for Galaxy Note