I use stun grenade a lot recently and may say that if you as my opponent for example dont't see the throw - you pretty much fu cked up but if you do and move a bit away or press retreat you are safe
Please stop saying this, it is completely untrue. As Mr. Smith pointed out if a single member of the squad gets hit by the blast the whole squad responds. If we had to avoid it with all models as soon as I see a Gren squad or a Vet 3 Sturm it would be back to base until tanks come out.