I saw a strategy on another site that suggested keep ~20% of a portfolio in a high risk instrument (XIV here) and the rest of the portfolio in a low risk instrument (cash, in this case). Nothing spectacular, but I'm sure there are variations on this that could produce some interesting results!

The blog article I found this on (and this version differs somewhat) was:

http://dontfearthebear.com/2014/07/02/barbell-investing-with-xiv-svxy/#comments