Do you mean front hub, or rear hub?
The problem with a rear hub is that i have read of instances where the threaded portion of the freewheel mount breaking off of the sideplate from too much mid-drive torque, applied too suddenly.
Doctor bass has posted that he has had slippage issues when he has applied more than 2000W to the front hub of a 2WD, so...2000W peaks is within the acceptable performance abilities of a geared hubmotor (which would be lighter than a 2000W DD hub).
I think there is a case to be made for a 2WD with a geared hub on the front wheel. The rear wheel can be a DD hub or a mid-drive, depending on the user profile. (hills? flat land? etc?)