Thanks Mike - That's almost exactly what I'm doing so I think I'm probably on the right track. I've been using that Blue Tubes limiter. It's not bad... But I downloaded the Demo of Elephant and plugged in the two side by side. Same exact thing you suggested with a separate project for the master, etc. Literally everything the same except the limiter. Then I adjust both as I would normally - even made sure the readouts were the exact same in Span. Then I mixed it down and listened side by side in my car, different headphones, my nice living room stereo, the crappy speakers I have at work, etc...
Voxengo was clearly the winner.
Bass sounds defined and smooth. Around 300-500hz was abrasive on the Blue Tubes version (could have been a problem with the mix, but for whatever reason Voxengo took care of it...) Also, looking at the wave forms in Audacity, it looks like I could have bumped the Voxengo version up even higher, whereas the Blue Tubes version would have been noticeably squashed...
I've only been at this a couple of years, and the reasons could have been some sort of setting or something - but Voxengo definitely got the job done and addressed some of the sonic issues that I've been struggling with...
I also liked that Voxengo has a transient shaper of sorts... I was able to dial in some of the things I wanted to do using that when I haven't been able to do it before.
That's what I'm leaning so hard towards Voxengo over Ozone... I can't imagine something performing better. And I'd have to get the Advanced version of Ozone which is 500. If I buy all the mastering plugins included in the mastering bundle from Voxengo, I'd only pay 300ish... (Elephant, Soniformer, Curve EQ, Polysquaher) - Would Ozone do anything these couldn't?