Double spin kick is 3 round lag on the assassin and two round lag on who he is fighting, just like pincer.

Balance in pk is easy as long as you pay attention to the 3 main elements.

Damage
Lag
Malediction

If you have two of them (in large amounts), than it is generally a good skill. Though there are some specialized skills that work great for certain situations.

The problem with throw is that it encompasses all 3 in large amounts (especially with the edges). Massive damage, malediction, and possible perma lag.

Yes, it's broken. But it wouldn't be that hard to fix.