I guess it depends what you do. I download 150Gb games on Steam on the regular, and can easily max out 1Gbps. Automated backups can easily max out the link in the other direction.
Will Steam actually download at more than 1 Gbps? (I mostly play games on an Xbox, and there the maximum download speed is less than 1 Gbps...).
Of course I also don't have any devices with 2.5G or 10G ethernet :)
