I seen 2 of d.Lloyd's dogs work ,and the ground he worked them on.
And I'd say the land ,and their prey drive .
They wouldn't catch with out the prey drive ,on the land though ,as it was as rough as the land can get.
My old bitch was nearly killed up on that land ,luckily she survived.
I can't see dogs lasting long no matter the breeding , but without massive prey drive they wouldn't get a sniff.
Just the way I see it ,d.Lloyd may have a different opinion though