I've had netting for 4 years, leisure battery source.
Lost all hens one year to a fox, but I think that I had a mole hill loosen the soil under the netting and the fox went under (it was pegged down, but pegs loosened by mole).
Just lost one hen in the past 2 weeks to a buzzard or sparrow hawk or similar.
Am just about to give up on it actually, due to the hawk, and the fact that it's a pain in the bottom to maintain (i.e. keep grass short, even though I do run a strip of damp proof course under the netting too), and to move.
And yes, some hens jump over it.
Oh and mine has killed two hedgehogs so far, even though I have un-electrified the bottom rung for them. And some frogs have been fried too.
So, in summary, nice idea but ... it makes you go "grrrr" a lot!
This weekend is being spent constructing a hoop-shaped run on wheels, with 12g galvanised mesh and skirt
.