Random thoughts regarding OPs question:
-If ETF contains companies that pay dividends, and is a short ETF, you get hit when those those companies pay dividends, where as longs do not.
-Most leveraged ETFs use some form of options/swaps in order to provide leverage - volitility in general has gotten crushed since 2009, but besides that, downside volitility is more expensive to protect against than upside in my experience - just do to the physics of the moves of underlying assets. So if volitility is getting crushed, and downside costs more than upside, chances are the leakage coming out of the short ETF will be greater than that coming out of long ETF.
Just my two cents.
-If ETF contains companies that pay dividends, and is a short ETF, you get hit when those those companies pay dividends, where as longs do not.
-Most leveraged ETFs use some form of options/swaps in order to provide leverage - volitility in general has gotten crushed since 2009, but besides that, downside volitility is more expensive to protect against than upside in my experience - just do to the physics of the moves of underlying assets. So if volitility is getting crushed, and downside costs more than upside, chances are the leakage coming out of the short ETF will be greater than that coming out of long ETF.
Just my two cents.