I recently purchased the NN5 and it's definitely a beefy unit!
I have my Canon 40D with WFT-E3A wifi grip on it.
I just got my pneumatic air mast (for pole aerial photography) and did a few trial runs. I sent the mast up with a motorized pan/tilt head, with the NN5 and Canon40D/WFT-E3A on it, that's about 10lbs of gear.
At 49 feet (fully extended) it worked great, eventhough I did have guy wires on the mast and it was leaning over a few feet (that means even more force on the joints on the NN5)
It worked flawlessly!
Here are my test shots (shot 3 is full extension of 49 feet)