As you would expect unmetered bandwidth from 100TB is truly unmetered and unshared, with no limits and no small print. Unmetered servers use exactly the same SoftLayer network as their 100TB equivalents and are fitted with 1000Mbit ports. Hosting plans page though has: Unmetered Bandwidth (324TB) add $399 / month
100TB a month = ~300mbps of constant use. The Unmetered upgrade means that you could saturate the full 1gbps for the entire month.
Except for the minor inconvenience that they cancel your account when you actually do that.