It can last just as long, like Backwoods Savage said look at all the old barns. Posts and beams frequently just debarked and put in. Fencing usually rots in the mortise and tenon joints and the fence rails themselves last until the moss finds it. I've opened up several walls in very old house's to basically find logs just cut on the front and back with the bark still on the sides with no rot whatsoever. Airflow, sun and top cover will be fine. Pro, logs/rounds typically split easier and are lighter. Con, can be a little harder on a saw chain.
