@vodoogroves: Not much of a difference. The debuff to doubleshot after using 10k stars was there for some time as far as is know. It just did not show. The debuff lasts for 45 seconds with the start of 10k stars which itself lasts for 30 seconds so you only have 15 seconds in which you have a lesser chance to throw one more shuriken. Since i only have the 10% Doubleshot from the feat because i could not fit more into my gear distribution i don't even notice it really.
@Spencerian: I'm not sure what minimum level your Freezing Gale Kama's were but i think this weapon proc only dropped at level 20 and above? If that is correct then you might also be able to use the ML20 shortsword "Star of Day" which you get for 15 Cleric Commendations in Eveningstar which has a chance to have Fiery Detonation on one of the two random weapon enchantments. This should work too. Would be nice if anyone could confirm this.