the tensioners are good for the sil tarps but if you have cuben it does not stretch under snow or ice. Not rain for that matter the wind can blow it in a little if it is really strong but it springs back to normal right after Also making sure you use some sort of spectra cordage will cut down on the stretch there
I am not sure of spinn texx maybe some one with a spinn tarp can say but i dont think it is supposed too either.
I am not a gram weenie. , But Im starting to see the merits!!!