It's a matter of SS vs crit' and it's not necceserly that easy.

SS affect your DoT, wich makes a lot of your DPS, the other part being how much Broil 2 you can fit into the fight while keeping miasma and bio and not letting every one die for simple beauty of flying little explosions. Wich means, it's certainly not worthless especially since you have to stack crit for it to start being effective and you won't be using your shields too much unless you really like not having mana.

If you want more DPS number, that may be a pick.
Healing wise, I'm not sure it'll do wonders (I'm actually quite sure it won't) since SS doesn't affect your instant burst heals.