Here we have the Ergomo-Sport and a PowerTap mounted on the same bicycle for the same ride!  We have marked them up together, same items and here is how they played out!

Ergomo Data vs. PowerTap Data

Ergomo-Sport

PowerTap

Ergomo-Sport
 

PowerTap

You can check out the data yourself!

Here are the .wko file from both power meters! You can use ErgoRacer or CyclingPeaks Software to analyze the data yourself!