OK so can you explain something. If you purchase the hk6 with no cut off for example,
When would it decide to go into hybrid parking?
If there is no voltage cut off won't it just continue recording until the battery is dead and that's it.
I still don't get the rationale of setting "no voltage".
Isn't it the same as using the battery pack wire
The dash camera doesn't decide to go into hybrid parking mode, that's a user choice in the dash camera parking mode settings.
With hybrid parking mode selected and when vehicle/battery pack accessory power is turned off, the dash camera will begin operating in Auto Event Detection [AED], Time-Lapse, or Low Bitrate parking mode until any of the "Cut-off Timer", "Cut-off Voltage", or "Cut-off Battery Percentage" [starting with firmware v2.1_260702] features have met their monitoring condition [time, HK6 Bluetooth published voltage, or VIOFO battery pack published charge percentage]. When any one of those cut-off monitoring checks have detected a parking mode transition is necessary, the dash camera switches from AED/Time-Lapse/Low Bitrate to Low Power Impact Detection [LPID] parking mode.
You can use the "Cut-off Timer" setting when the dash camera is powered by the HK4, HK6, or the VIOFO battery pack dash camera power cable.
You can use the "Cut-off Voltage" setting when the dash camera is powered by a HK6.
You can use the "Cut-Off Battery Percentage" when the dash camera is powered by a VIOFO battery pack [BP100 for example] and the A329S/T/WW/TC firmware is v2.1_260702 or later
The HK4 and the HK6 hardwire kits have their own low voltage cut-off feature. As you mentioned there is a modified version of the HK4 or HK6 that replaces the 12.4V low voltage cut-off setting on the hardwire kit module making it operate with the low voltage cut-off feature being disabled. The hardwire kit's low voltage cut-off feature is intended to be the thing protecting your vehicle's battery [when it obtains power directly from the vehicle].
When the dash camera's parking mode is set to "Hybrid Parking Mode", the dash camera's "Cut-off Voltage" setting will be the voltage level that the dash camera will transition to LPID parking mode. When the dash camera's parking mode is set to AED, Time-Lapse, or Low Bitrate [not via the Hybrid Parking Mode selection], the "Cut-off Voltage" setting will result in the dash camera powering off instead of switching to LPID parking mode. See pages 49-52 of the A329S user manual for a chart for those settings.
You'll notice the A329S "Cut-off Voltage" setting options are very limited [12.4V/24.8V; 12.2V/24.4V; 12.0V/24.0V] since that feature is primarily meant to be used with a hybrid parking mode configuration and it being the voltage level to transition to LPID parking mode.
If you're powering your dash camera with a dash camera battery pack, there's no direct/real need to have the hardwire kit's low-voltage cut-off feature functional. The lowest voltage level the HK4/HK6 hardwire kits low voltage cut-off feature can be set to is 11.8V. A dash camera battery pack can safely provide power into the low 10V range. Setting a modified HK4/HK6 to 12.4V via the slide switch on the hardwire kit, that disables the low voltage cut-off feature allowing the dash camera to get additional parking mode runtime [11.8V down to low 10V range].
I hope that helps.