I for one haven't even tried it. I know Thyraz was using it, not sure if he still does. Just not into getting locked out on two schools for a minor dps increase, maybe when we get more haste in a season or two.
How many people over here do really use stellar flare? I tried it and the damage seems meh. It feels like I'm dealing more damage with Euphoria granting that -20% cast time on empowered Starfire and Wrath.