Quote from Chagi:
Yup, they are indeed interesting products. The double beta inverse ones should be particularly cool.
http://www.elitetrader.com/vb/showthread.php?s=&threadid=55054
At the risk of sounding like an idiot, I'll ask: What's the pt of an inverse product other than being able to have a hedged position within a single account? Don't you think that giving longs the option of not hitting out of the SPY when it's going down would lead to lower volatility?