Thanks MG, yes, I have Ozone Insight.  I'll follow up your suggestions.
There are just SO many variables that have to be brought into equilibrium!

In fact the waveforms on their respective bounced X3 tracks look almost identical. I was wondering why this is?

what the waveform looks like does not contribute to how loud it is. The wave form is just a representation of the audio. It has nothing to do with loudness. also, you can have 2 songs that both have an RMS of -10dB and one will be louder than the other.
 
Loudness is not measured with wave form pictures and its not measured by RMS levels. Its measured with your ears. so the only way to make all songs the same level is to use your ears and not by looking at the waveform. 
 
CJ

If you can read this you have one technical reason this can happen. Meters measure "energy" ultimately sound pressure coming out the speaker. Your ear is not equally sensitive to the same amount of energy at all frequencies. Unfortunately, if you are designing for the human ear as an end user, you cannot use a simple energy meter. It is best to use a good pair of end users.
http://en.wikipedia.org/wiki/Equal-loudness_contour