SSO versus UPRO in M3....9.2.14

One of the factors I'm reviewing in M3 is the use of SSO versus UPRO as the mid beta input between SPY and XIV.  UPRO versus SPY is a much more reliable and profitable pair than SSO versus SPY and below are runs of M3 using SSO and UPRO as the SPY leveraged outlier.
SSO is 2X SPY and UPRO is SPY 3X so we'd expect the drawdown factors to be reflected according...which actually is not the case as can be seen below.
In fact, both mid and longer term returns are somewhat enhanced using UPRO in lieu of SSO.

There are a couple caveats to using UPRO instead of SSO and those include UPRO having about 20% of SSO's daily volume and a much thinner open interest and much greater bid/ask spread in the option chain.
On the positive side SSO and UPRO are less than 2% apart in price (120.90 vs. 122.30) and the bid/ask spreads of both SSO and UPRO are .01 and .04 respectively.....not a deal breaker.
Note in the rankings that UPRO assumes #1 ranking on 8/25 and 8/26, which is largely responsible for the improved performance metrics.