Two high torque geared hubs looking [marginally?} suitable for an off-trail ebike are the 3x3NINE and the Revolute Hub1 which has 6 speeds. Both list max torque at 250Nm. The 3x3NINE though could not be found for sale yet (cost is ??), the Hub1 costs about $1100.
A means of calculating hub suitability for max torque needed is to look at how much torque would be needed to climb a 45 degree slope. Never mind the traction issue. Your Big Ass aside, let's choose a weight of 100kg for bike, motor, battery and rider. Approximately, we find...
The force downward is 9.9 x 100kg = 1000N,
Resolving the needed traction force at 45 deg is 1000N x sin 45 deg = 700N
The torque input for a 29" wheel (say 15 inch tire radius) becomes 700N x 15/39 = 270 Nm
So 270Nm is > than 250 Nm. Safety factor = .92. I prefer designs with a S.F. = 2.
Spikes in torque [shock loading] arise when hiting a headwall(vertical walls or rock etc). Depending on the local traction these torque spikes can exceed the typical hill climbing torque needs. I once tore a Lightning Rods Gates belt apart headwalling.
My QS 3000 edirtbike and I may just barely exceed 100 kg. The wrench torque needed to remove the White Industries Ultimate free hub is about 300Nm. The hub removal torque for the the QS 2000 edirtbike is say 200Nm. Both these builds get difficult climbs with headwalls never a continuous 45 deg slope.
The bottom line as to the suitability of these new hubs for off trail use based on the above data is that for a light rider and bike with not to strong of a motor (3000 watts) you are likely okay to marginal. I may try the Hub1, who needs 9 speeddds with a motor?
One test for off trail use is whether your bike setup can do a full weight burnout from a throttle twist begining at zero. My Cyclone 3k that is one speed geared to go 30+ mph cannot. It is not fully suitable to off trail starts, but likely with one of these geared hubs the torque would be sufficient?