I agree with ysp8th. See my comments from the DXO board on why I shorted UCO rather than going long on a short ETF (3rd paragraph):

http://messages.finance.yahoo.com/Stocks...

SCO would give you better returns during a consistent downtrend due to compounding, but shorting UCO is much safer - even if you get the call wrong, you're almost guaranteed to make a profit eventually by just holding, the only way you wouldn't is if oil just continued in a steady uptrend to much higher prices and never looked back, and that's simply not going to happen. Besides, even if (as I believe) the trend is reversing, trend reversals usually start with a lot of choppy up and down price action, which would eat away at profits from a long SCO position, but *magnify* profits from a short UCO position.