I think in most cases a front camera is just fine in case of a crash, it might not capture the guy T- boning you, but it will capture that you are just driving along and do nothing out of the ordinary.
So what ever go down you will always be able to prove that you are in the clear, the other part will probably try to claim ( and just let them lie all they can )
1. you ran a red light
2. you was swerving all over the road, or tried to change lane abruptly
3. you was stomping the brake
And what ever a dishonest person can come up with to try and save their own ass, but whatever they claim you will be able to shoot that down with just footage from one front camera.
So i would say you are better off with a good single camera then you are with a mid range dual camera.
Myself i have my car crammed with cameras, but i just use them to expose on youtube all the WTF that go on around my car, for liability purpose my front camera should be just fine.
Actually i was rear ended over a year ago, and my rear camera did not work at the time
but it was no problem the guy took blame at once and my insurance company still liked the front and Right side cameras, Danish insurance companies are not geared towards handling dashcam footage.
And the police liked the footage of the guy i reported to them braking so many laws in 20 seconds they could drive strait out to him and get his license and in turn hand over a hefty fine to the idiot.
Just remember a dashcam are not quite install and forget, you will have to take a look at the footage on the memory card now and then, and a in camera format of the memory card is also good to do once in a while.
And i like you are caring about your grandmother, that is sadly becoming less and less common as i grow older, and i have no kids or grandchildren so thank god my sisters kids love and respect me.
