Not worth the $0.05 per hour when it can't get back to the trees successfully without intervention most of the time. It just goes to the cabbage pen, clicks to the trees, then clicks back to the cabbage pen before it even makes it to the trees. Terrible pathing. Seriously, 159 planks in 20 minutes is pathetically slow.
I banked ~35k teak planks and got 99 con with this on my iron. Pathing was a bit weird at times, and like dogdog said the plank sack support would be really nice. Other than that, it's really nice, especially for ironmen!