The answer is simple, Tentsile poles take part of the load of your bodies once they are in the tent.  We chose aluminium poles partly because the ferrels are on external and therefore do not catch on the poles sleeves and partly because they of higher quality than any fibre-glass ones we could find. They do bend though.  Many people seem to set up their Tentsile with still quite a lot of slack – like a hammock. It is not a hammock.  The poles will bend to breaking point if the Tentsile is not set up tight – it needs it!  Think of it like a platform with a roof.  In the case of the Stingray and Connect models, the roof also partly holds up the weight of the occupants. Embrace the bend, it shows the poles are working hard!