Because of the low liquidy of TMV and SPUX, last night I looked at TBT and SDS as alternatives as they appear to be much more liquid. But their returns were about 100% less (350% vs 450%) over the 5 years worth of data. Still good returns, but lower. I tested a few other options. Adding TVIX or VXX adds a little to the performance with more volatility (ha...). The author appears to have picked the best instruments from what I have seen so far.