Well the G-sensors can be set pretty sensetive i think, but then a passing truck or bus may trigger a recording.
And i am not sure if it can be set sensitive enough that a person keying the car will set it off.
Motion detect on the other hand will triggger even if a black cat walk on a fence 10 meters in front of the car, but problem with motion detect is they trigger a lot of false recordings, anything moving in front of your camera will trigger it.
But offcourse it is better to have too many recordings than none at all, good thing is event triggered recordings will be tagged with a suffix or end up in a special event folder, so they are easy to tell apart from all the regular recordings.
As to reviewing the footage, i hope you get up erly then, if you review at 1:1 speed it will take as long to go thru the material as you was recording it.
In regard to dual systems it seem all of the ones on the marked is plauged with some technical issues, some work best with only some brands and models of memory cards, other ones have other issues, and they all seem to be made with 1 "large" main unit for install in the front window, and then a rear camera thats usioally pretty nice small tied up to the front unit with a wire, and thats for the most a USB cable providing power and returning video from the camera to the storage in the main unit.
Main contender dual channel systems. ( with prebuffered event recording, meaning you get a fjew seconds of what happen before the triggering event )
Panorama X2
Lukas dual systems ( can not remember ther model numbers )
Honorable mention single channel systems.
Street Guardian SGZC12RC, it have a main unit with screen and a small discreete camera on a wire, and it support prebuffered event recordings.
This camera can now be fitted with cameras in a small alu housing thats water / weather proof, i think the size of it is about 1 x 1 x 1 inch
Not sure if they sell the SGCZ12RC with the waterproof camera, but they seem to be dealing with cool guys so i am sure you can strike a deal if you try one of those.
If you park reversing into a slot i assume you can make do with a front camera as most will pass by it getting to and from the area of your car, but offcourse if you park at a mall type parking lot with cars on 3 sides of you that might not be enuff.
I feel your pain M8, a couple of days before i sold my old 4x4 it was keyed all along one side by a treehuggin punk, so i have to take a dive on the resell price.
I then got a new car, and it had the window in the front R door smashed about 2 months after i got it, and it now have a dent in the roof from some idiot trowing a D type batteri high up in the air and then landing on my roof.
Resolution rambelings, 720p is not that bad, but really you should look for 1080p thats the norm now for good dashcams, just be carefull cuz there is allso a lot of 1080p dashcams out there thats not worth the price of the parts in them and sure not the price they will be asking for them.
I mentioned SG as they are aussie, but they are allso some of the serious ppl out there, they could have rushed a dual system to marked last season. but they preferred to stay clear and wait untill they can do it right the first time, and they offer service and customer care second to none i heard off.
And they are for sale in parts stores here and there in the land of Oz.
The user
@jokiin in here is the man at the helm of the Street Guardian ship, He is a nice guy, and he is brewing on a dualsystem that i think will be inline with stuff you can use, but it will not hit the streets before winter ( aussie winter ) at best.
And if his up and comming dual system can use the waterproof cameras from current generation it will be perfect.
Australia is my adopted home country or first choice if i ever can afford to leave Denmark, long before some of them started to send me dashcams, and long before i had 2 days in Freemantle before my ship left port.