I should add a bit more detail, its the location services you want to untick.
Unticking the options in there wont affect how you use maps, its more to do with how maps tracks you. I use google now, so having these options ticked helps google now supply me with info.
As long as you have GPS on then you shouldn't notice any difference in your maps experience. GPS only uses battery when an app requests it, so having it on all the time wont affect your battery when the phones not in use.
9% drop overnight will be ok for some people, it all depends how people have their phone setup. I guess the only time you can do a like comparison on battery is when the phone is out of the box, without any options tweaked and without any apps downloaded. I have my phone plugged in every night, so this isn't an issue for me.