It can be very useful.
Let's take the Dread Guards in Asation HM for example, when Kel'Sara casts Force Leech and you still have the probes on yourself from your Op/Scoundrel healer, FC will put a debuff on you that grants you almost 0 healing and you immediately lose aggro, you can then proceed to just click those probes away and step back in.
Force Shroud gives you 100% protection against the "death by healing" phenomenon. When I run with shadow tanks in this fight, I usually tell them to pop it as soon as Force Leech lands, just to cover healing mistakes. It also gives them time to click off HoTs and what-not.
The problem with using Force Cloak is the cooldown is too long to use at every Force Leech, whereas Force Shroud will always be up.