Shadow copies won't let you restore your server if it fails, no. It's primarily to support "Previous Versions" functionality, which allows you to go back in time to a previous version of a file or folder. It's also used for system restore points
on desktop operating systems. But Previous Versions and Drive Extender are incompatible. There's a workaround that will get you access to them, but it's not 100% reliable and it's unsupported.
I'm not on the WHS team, I just post a lot. :)