No matter what numbers Elite XC does, there will be people spinning it either as a success or failure as long as the show does above a 1.5.  But what is a real barometer of success?

It is true that Summer Saturday Nights are not typically high rated, but it is also true that May 31 is not exactly in the middle of Summer.  Major finales are running that week, such as "Lost" on ABC.  The end of May is not exactly the graveyard yet, especially given the extended seasons resulting from the WGA strike.

However, we can take an example from the absolute middle of Summer, a weekend of historic ratings lows for the networks.  On July 7, 2007, NBC aired "Live Earth" and did 2.8 million viewers.  Considered a bomb:

Anything below 3 million is a bad number given network weekend standards.  Anything between 3 and 5 is probably closer to "solid" than great, but it will be spun as a massive success.  If they manage to pull off a number above 5, then the whole industry is going to be changed.  

Of course, as others have pointed out, show 2 may be the more telling number than show 1.  With the show coming less than 2 months after the first, it will be very interesting to see what kind of rating they are able to sustain.