Yeah. i would go for the real deal too, and it will be the first time i try parking guard in my car.
I haven't really felt a need for it as i have CCTV on my car where its parked at home, and the back yard are pitch black so parking guard in a dashcam wouldn't see much.
And it is very rare i park out on the town, and if i do its most likely in a parking garage that also have CCTV.
Plus i drive a mini car ( suzuki ) and so its battery are mini too, and the damn thing are 6 years old by now.
If you already have the DC you can just go with the PSU and a quick install tucking the wire out of the way and then swap for the hard wire kit when it arrive.
As i recall my install of the DC took 20 minutes in my little 5 door hatchback. installing the hard wire kit will be a drag as my fuse box are put in a really silly spot where you have to be a contortionist to work the fuses.