Personally i think they are pretty good.Not only do they improve your aim and accuracy,but also help your sniping aswell.If you need more help go on youtube and search for fps freeks there's tons of videos on there
Gamebattles WILL ban you for using a mod simply because you have an advantage over other players....i remember asking a ref about it and he said you'll get banned
If by any chance you manage to jtag your xbox could you do me a favour and get my friend a 10th prestige.....sick of people saying they will do it and then try and scam you...just pm me..thanks man