Don't know about the greys but my GF just had her 4 year old certainteed siding removed. It cracked and warped all over within the first 2 years. There was a class action lawsuit regarding the product. She was given a settlement amount ( but had to add to it out of her own pocket). She replaced the siding with Hardi-Plank. The whole settlement and residing process caused her a lot of stress and hassle.
She was told that there was a problem with the siding for a couple years because Certainteed had changed their product formula but now have changed it back.
Just thought you might want to know this info.
I have had Hardi- plank on my house for about 5 years and have had no issues.