I have just purchased a Garmin "DriveAssist" 50LMT. Did so for a variety of reasons. Some things to consider before making a decision:
1) In general most seem to ship with barely-enough power cable length to reach the accessories/cigarette power outlet when you simply root the cable down the center of the windshield/dash and drop down to the outlet. It's annoying because companies like Garmin also sell a separate 5m (16') power adapter which is easily routed to the passenger side along the top of the windshield then down the right hand side where the windshield meets the post, then under the dash and over to the center console. Cost of the separate adapter is about $23, but of course then you have the original power adapter left over. I will go with the default until I confirm all my assumptions, and am keeping an eye on a accessories/cigarette outlet extender, which are much cheaper and usually from 10-15-20ft.
2) I already had a few spare 64gbyte class 10 microSD flash cards (photography), so am popping out the now useless 4gbyte card.
3) Hoping that you can Leave the camera on it's mount when you are not in the car probably isn't going to work out. Most thieves are looking for multiple items, and even at night it's still easy to find especially if they carry a small powerful LED pocket light. (Which they do since it means taking way less time to peer into the car. I'd leave it mounted for quick stops, but probably will store it away if going to Costco on a Saturday afternoon. During the holidays.
4) Whether or not the mount itself remains stuck to the windshield is going to be a function not only of temperature, but of temperature variations over time. The rubber/glue/suction is most like to deteriorate over time when the temperatures vary alot. I worry more about it giving way in freezing cold than in heat.
5) Overheating: First, if you don't take the chance with #2 above and remove the device from the mount while not in the car for extended periods then most likely you will be using A/C to cool the car down as soon as you get in, and even use the windshield defog setting at the same time. While driving, your car would have to be heading in a bad direction at the right time of day to worry about it. So yeah if I'm driving in Texas during the weekday, heading south at say 2pm, in traffic, it might start to overheat. At other times of day the sunlight will generate much less heat penetration. If you are travelling in a non-straight line etc, there usually wouldnt be hour+ constantly increasing heat.
One final note: there are some good Youtube videos on how to route your power connection around the windscreen. It's non-specific to any automobile.
More info once I gain some experience, and hopefully new wisdom, with regards to the reality of what I've just bought.