I have the G-one 700x40c (70 psi max) on my BH gravel bike (Yamaha PW-SE drive). On the same bike I can only compare them to Continental Doublefighter 700x35c (87 psi max) and Continental Gatorskin 700x32c (100+ psi max). The G-One seems like a decent tire with reasonably good traction on gravel, smooth on pavement. Trade off is rolling resistance. One of the tires developed cracks exposing the cords - Schwalbe replaced it even though it was almost 2 years old and somewhat worn with over 2400 miles. While waiting for the replacement I put the Doublefighter on the rear (87 psi max). I usually run near max rated psi so the ride was stiffer and looser on gravel as expected with the thinner tire and less rolling resistance. Of course the Gatorskin had much less rolling resistance than either of those but obviously not for gravel and the ride was brutally harsh on anything other than smooth pavement.
I won't need replacement tires for this bike in the foreseeable future but I doubt that I'd go with G-One again, not that there's anything wrong with them.
Probably not helpful info for you but it's all I got other than I've had regular Marathons on other bikes-wear like iron but not really for gravel.