Doesn't seem to be any overwhelming demand for preorders. I had forgotten about my invite, and when I remembered that evening I clicked the link and easily pre-ordered.
It's nice that we don't get charged until the order is shipped, so I am sure we will know by then if/how much GT7 is supported. If it's anything less than 100% I will cancel the pre-order. I already have a Rift S to have fun with the family on PC. No reason right now to spend $550 on another headset if GT7 is not supported, or lacking in implementation.