Yeah i have no problem seeing that setup on bicycles & motorcycles too, but i am not sure it is a all weather setup or i have problems seeing how they can make the front unit waterproof when its tethered to the rear camera.
Waterproof without a case would be good, but unfortunately the Git3 will still be a fair weather camera when used without a case, that is about the only thing that justifies the price of the GoPro Hero 5! I think a waterproof case that allows for the cable to the slave camera will either need to be too big, or only shower proof...
If the GIT3 will have EIS on both cameras it would make for a great hiking camera, one can go on the chest or front of you and the other camera can be mounted off your backpack and point in any reasonable direction.
BUT i am not sure if that can be done, it will off course also demand a oversized sensor for the rear camera.
The slave sensor is only 2MP so not enough resolution for gyro stabilisation, and I don't think the processor can manage 2 stabilisations anyway. Plus you would need an extra gyro sensor in the slave. I think you are still going to need 2 full size cameras to achieve that. Stabilisation isn't so important if the slave is only viewed as picture in picture though.
Regarding GIT4 we share hopes it seem, there seem to be plenty of the regular 4K cameras out there, even if you factor out the "4k" ones, and 1080/60/120 also have good coverage with a horde of cameras to choose from.
A well supported and build git4 as we dream about will be cool, even if its just 100 dollars cheaper than the virb 30 or the gopro 5 cameras, cuz it would still 1 up their performance and beat them on prize too.
If you put it on par with the virb 30 and GP5 on prize and just offer EIS for 4K and 60 fps, then i think it would struggle some, or at least more than if the housing said gopro 6 but otherwise had the came features.
I guess GoPro will produce a 4K 60fps version of the Hero 5 sometime this year, maybe with 4K stabilisation, Yi have already made their announcement although their specification still doesn't manage stabilisation at 4K 60fps! The Git4 will need to be cheaper than the GoPro to compete, how much cheaper depends on how waterproof it is without the case, the Garmin is waterproof so can be very close in price.
PS. In regard to dashcams i wouldn't mind a 4K one, or maybe it should be labeled as a journey recorder as it will off course lag some in low light performance.
But for daytime driving and fitted with a lens not quite as wide as dashcams, i would take it for sure for stellar daytime footage.
Yes, a 4K dashcam would be good, although I imagine most people would stick with 1080 so the market for it may not be too big. With 4K you can actually have a wider view since you still have plenty of detail when you zoom in (or look very closely at your 4K screen). Git3 dashcam footage is actually quite good in the dark, the front sensor (which is a decent quality 4K sensor) gives a nice image, although if you want to read a moving number plate in the dark then you have to hope that the slave camera has captured it since the main sensor does suffer from a lot of motion blur when things are moving fast or get close. Using 4K helps because you can read the plates while they are still at a distance where they are not moving across the sensor very fast so the motion blur is a lot less.
Provided off course that the 4K/60 footage get dumped on a ssd, cuz i just cant see a SD card being used in such a "dash" camera.
The Lexar 633X micro sd card in 256 Gb cost +2000 DKkr here, for those money i can get a 512 Gb ssd.
The price of those 256GB micro SD cards will drop considerably once the 512GB 3D NAND cards arrive, I'm sure Samsung will release a 512 this year to stay ahead of everyone else who are now releasing the 256 cards. The manufacturing cost can't be any more than for the same size SSDs, probably less since the cheaper SD cards can be a lot slower.