Stu, Thats what I'm saying even one that meets specs 2.5mm wall thickness can bend because cds has a higher yield strength they drop the wall thickness down which is nice and light for comp but giving it stick off trees can bend. I've see 2 people been told to go home and Tag removed from cage. New cage and you can play again. Alot of people are starting to go with thicker than minimum spec wall thickness keeping cds as it can be bent nice and tight just for the peace of mind and durability fit once last 10 years+ Older type blue band/red band steam barell to BS1387 has a much thicker wall at 3.2mm tough as bouncing off trees all day every day but has a weight penalty and cannot be bent as tight as it crushes. There is alot of snobbery around cages and materials both have good and bad points.
Just thought I'd mention as its not talked about much, its worth noting when looking into cages there is alot of snobbery that CDS is so much better but it has its bad points also that need to be explained before you purchase