Unless the shadecloth prevents snow from sliding off the roof, I can't see it creating an overload and if it did accumulate too much, you could always brush off the excess and if you have the GH shut down for winter and the shadecloth really does aid in preventing wind damage, it would seem to me; that even if a shadecloth wears out sooner from winter exposure, if it also prevents major damage to the GH, leaving it up makes perfect sense.

Shade cloth as cargo net- but whatever is easy- and works.

I remove mine because it will prevent the snow from sliding off the roof.
When we get a heavy snow I use a kerosene heater to bring the temp up to about 80 for awhile and the snow just slides off.
The 10x12 HFGH has a steep slope if the roof is smooth some heat will get rid of the snow load.