Not DI, but I've used some of the ultra-short sector funds.  I prefer them to the ultra-short market funds.  But the effects of leverage are still unpredictable. 

Same holds for the ultra-longs.  They don't always track the regular sector funds like they should.  It's maddenng to see the regular ETF has gone up 2% and your "ultra" fund has gone up only 1%.  I still don't know what causes the mismatch.

But a caution for the lurkers, ETFs like energy are volatile enough in themselves.  Adding leverage can scare away the uniniated after just one or two days of the market going the wrong way for them.