I'm not sure FUSE is all that useful for that. It still goes through the kernel and additionally roundtrips through userspace again. I think the only advantage is the convenience of not having to do kernel development to make a filesystem. I.e. anything you could do with FUSE, you could do in the kernel with fewer copies and context switches.

I'm also not aware of any FUSE filesystems that directly access block devices. They usually have network or other filesystem backends.

Ntfs-3g uses FUSE and directly accesses block devices.